AQA GCSE 'Predicted' Paper 1 - FULL Walkthrough - Live

Ajouté : 2026-05-28

[00:01:23]Hello to everybody watching this live and also those of you watching the replay on YouTube. So today what I'm going to be doing is a predicted paper uh ready for GCSE physics paper one that you've got coming up very soon. Now, the paper that I'm going to be using is one that you can find on PMT. So, this is freely available. All you need to do is go to their website. You look under their resources, their predicted papers, uh, and then you basically sign up for free, you get an account, and then you can download it. Now, um, what I'm going to say at the start, I'll probably say several more times during the stream, is that although it says the word predicted paper, I don't think in my experience as a teacher that you can accurately predict exactly which topics or questions are going to come up in the exam. However, this is a good way to revise because there are some kind of similar topics that might come up, some kind of standard physics questions, and if you're happy with this, it means that you're really well prepared for the real exam that you've got coming up. Now, um, yeah. So this thing here, although it says predicted, I don't think that you should use this as a basis for all of your revision, the best way to do really well in any exam that you've coming got coming up, if that's any of your GCSE subjects or your A levels in a few years time, is basically to revise everything and expect anything could come up in the real exam. Now what I've done as well um is because I make physics videos for GCSE and A level I do have a complete website with over 500 videos that cover every aspect of GCSE physics and that's called GCSE physics online. I also have as part of that let me just show you before we start with the actual question paper itself. I also have a series of practice papers that I've written um which are specifically for AQA physics looking at the higher tier content um and especially for those doing the triple science the separate physics. So, um, basically what I've got is, um, I've got these papers here. These ones here, um, really aimed at students wanting to get maybe go kind of secure that grade seven, maybe get a grade seven, an eight or a nine. Um, and basically what I have are question papers that you can download. When you download that, you also get the mark scheme. So, I've got the the kind of exam kind of mark scheme that you're going to be familiar with, but this is written for students. And also included with that I have a set of my work solutions. So you can see how I'd approach similar questions if I was a student doing the real exam. So I've got all of that. I've got show I show where all the marks are available and so on. So basically what I have are a full set of practice papers for paper one and also paper two aimed at AQA physics paper one and paper two. Now um just to sort of show that in a bit more detail basically I've called them alpha beta gamma delta epsilon and zeta which are the first kind of six letters of the Greek alphabet. And so what I have is I've got six practice papers for paper one and then I've got six practice papers for paper two. And um basically this is kind of like the kind of content I've got. So basically this is how I split up all of the content over these six papers. Now you can't predict exactly what's going to come up but you know the kind of topics because these are all the things mentioned in the specification. And so basically um with a paper there are 10 questions in total.

[00:04:47]And so for the first practice paper which I've called alpha um the first question is about atoms and isotopes.

[00:04:54]The second one is about one of the required practicals. Then we've got changes the state in the particle model.

[00:04:59]And by mapping out all of the content in the specification over these six practice papers, there are multiple times when you can do the same kind of uh questions about that kind of topic.

[00:05:09]You can also see the ones I've just highlighted are all of the required practicals that you need to know about and the variations of them. So, um, there might be five or six required practical that you need to know about, but there's one here where I've got a question about resistors in series and parallel. And then I've got, um, another one here about the characteristics of a diode. Uh, we've got the resistance of a length of wire. We've got a practical about the IV characteristics. We've got another practical about the IV characteristics. So if you did all six papers or at the very least read through them and read through the model answers, you would see all the kind of possible combinations about these kind of required practicals that could be asked about in real exams. So if you want to find these, I've put a link uh in the description of this live stream. Uh but if you really want to go from that grade seven to a grade eight or a grade eight to a grade nine, you want to guarantee that success, you may be thinking about Alevel physics next year, have a look at these.

[00:06:07]Okay. So, um just responding to some comments so far. Uh where can where can you get the questions? Good question. Uh so the questions I'm going to be going through today you can download completely for free from PMT. Uh so physics and math tutor on their website.

[00:06:23]This is the AQA paper one predicted paper. Uh can I create a video for the AQA Alevel physics paper 2? Yeah.

[00:06:32]Basically what I'm going to be doing is more live streams uh for the next couple of days. Um, today I'm doing GCSE.

[00:06:38]Tomorrow I'm going to do an OCR Alevel physics live stream at 2:00 going through the exploring physics paper. On Friday at 2:00, I'm going to do an AQA predicted paper uh ready for paper two.

[00:06:52]Then on Saturday morning, I'm going to be doing a free A-level class about capacitors. Saturday afternoon, Joe is going to be doing an Alevel ED XL math master class. And then Sunday, I'm doing three master classes for OCR, AQA, and ED XL ready for the Alevel exam on Monday. And for those of you watching this who are GCSE students, on Monday afternoon, I'm going to do a mega revision session uh on YouTube completely for free the afternoon uh before your big paper one exam. Okay. Um somebody says they are a physics graduate student. Will this question help me? Um I think it's always nice even if you have done physics before to look back at the stuff you've done at the time. Okay. Yeah. So right um so let's start with question number one. So um I don't work for PMT. I'm not affiliated with them in any way. Uh apart from that I've done some resources which they've got on their website. I think they're they do lots of valuable stuff but I'm not being paid to do this.

[00:07:49]They're not paying me. I just thought this would be a good set of questions.

[00:07:53]So, the first one, we've got um a roller coaster where you've got a cart that's got a mass of 500 uh kilograms. We've got a height of 20 m uh and it reaches a speed of 12 m/s.

[00:08:09]And the first thing we want to do is calculate its kinetic energy. Now, anytime there's any kind of a calculation, it's a really standard process. The first thing you need to do is look in the data sheet and write down an appropriate equation. For this one, we can say that the kinetic energy EK is equal to a half MV^ 2. Okay, so basically I've written down the equation given to me in the data sheet. Okay, I don't need to write it out in words. I'm just going to use the symbols. Um the other thing here is that we need to think about what's the data. Well, we've got the mass of 500 kg. So that's m and it's got a speed v because we use the word v to represent velocity or speed of 12 meters/s. So I've written down um the symbol for these and I've underlined the key data. You could of course uh just highlight the numbers uh with a highlighter as well just to kind of make sure you've actually captured that data.

[00:09:08]Then of course we're going to use the equation and we're trying to find out the kinetic energy. So the kinetic energy is going to be a half * 500 * 12^ 2. And it is only the 12 that we're squaring. And then when it comes to putting the numbers into your calculator, I'm going to start with 12.

[00:09:25]So I'm going to put 12 squared is equal to 144. Then we're going to multiply that by 500 by.5 giving an answer equal to 36,000.

[00:09:37]Uh but that's not the answer. The answer must also include units. And therefore, we're going to put a capital J to represent jewels. So, the first answer, easy, straightforward, 36,000. But it's only easy because you've got the right equation. You've identified from the question the key bits of information you need. We're going to put that into the equation, do the calculation, and then just think about a unit at the end. If you do that for every single calculation, you're going to be 100% correct in them all. So, you go 1.1 nice and easy. Um, at the end of the track, it says here that the cart compresses the spring. Explain what happens to the energy of the cart as the spring is compressed. So, I guess this question here is about energy stores and transfers. Now, initially, just before the cart hits the spring, we're going to have this massive store of kinetic energy because something's moving. And then as the spring compresses, this is going to be transferred to the elastic potential energy store. So, let's put that in a sentence. Uh so, what we've got here uh is not elastic to kinetic but kinetic to elastic. Okay. Um we can say the initial uh kinetic energy store of the cart is transferred to the and this takes a lot of time to write out but just try and think about how many how few [snorts] words you can use. So, uh the initial kinetic energy store of the car is transferred to the elastic potential energy store of the spring.

[00:11:39]Um and that's pretty much the answer. Uh and I guess if we think about what's actually happening here is we've got um the first store is kinetic energy. The final store is the elastic potential energy store of the spring and that's provided the spring was to remain completely uh compressed. Um the kind of transfer this is is going to be mechanical work because we've got a force acting over a distance which actually slows it down. But I think for two marks an answer like that is appropriate. Okay. And by the way if you want to put answers in don't worry if you get it wrong. Um yeah, somebody says, "This is so helpful." Uh says, "Matty, uh I just went to revise physics." Yeah. Uh somebody, um somebody has got physics and maths on plus two.

[00:12:25]Yeah. Basically, uh if you want to put answers in the chat, I'll keep an eye on it during the stream. I'll do my best to read stuff out. Doesn't matter if you're wrong. It because you know um I don't think anybody can tell who you are from your name. Your teachers don't know that. You're not getting graded. Just see how you get on. Also, let me know in the chat. Is everybody at the moment incredibly hot? Because at the moment, my office is okay, but I might just go and open the window. Now, I don't know if I open the window if that's going to let a cool breeze in or if it's going to let hot air in. So, I'm just going to open the window and then we'll get back to it.

[00:13:11]Right. Then, uh, somebody says, uh, Matthew says, "You're outside and it's boiling." Yeah, it is. Today, I think it's pretty hot. I think tomorrow gets a bit better. I've opened the window and at the moment I've got a cool breeze, which is lovely. Uh, I'm just going to get a quick sip of cold drink that's been in the freezer.

[00:13:30]So, yeah, hopefully I won't look too hot and sweaty on the video. Right.

[00:13:35]Talking of which, question 1.3. It says, "A metal part of the ride increases in temperature when energy is transferred to it. The metal has been chosen due to its high specific heat capacity. Explain why this metal part should have a high specific heat capacity." So, um, if you're not sure about any terms here, you can of course look in your data sheet. What you'd see is that E is equal to M C delta theta. Uh so this is the equation looking at specific heat capacity where specific heat capacity C is equal to the energy transferred to a mass or a kilogram mass of something um that goes through a certain change in temperature. Okay. So what this means is if you've got a high specific heat capacity, it takes a lot of energy to change the temperature of something by one degree. Uh and this is something that's actually relevant. I mean, in Bristol yesterday, there was a bridge.

[00:14:33]It's like a swing bridge that moves around, but it got stuck because it was so hot that the metal parts of the bridge expanded and they kind of closed the gap and they basically had to get fire engines to kind of spray water on the bridge to cool it down. So, why should the metal pot have a high specific heat capacity? Uh we could then say that this means um it can absorb um a lot of heat energy and only have a small temperature rise.

[00:15:20]So that's the first bit. Why is that important? Well, imagine uh you've got a structure that maybe is made out of bits of metal like this. Now, if the temperature increases, the metal expands. Now, what that would mean is if all of these expanded maybe by 10%.

[00:15:39]Uh rather than the structure of this fairground ride being kind of completely solid is that the top bit might get a bit longer. the bits at the side might get a bit longer and then everything kind of starts to deform. And what you want to do is reduce that as much as possible. So if you've got something with a high specific heat capacity, it means that the temperature rise is going to be minimal and therefore there's going to be um no change in the dimensions of that thing. So it keeps everything as it should be. So this means it can absorb a lot of heat energy and only have a small temperature rise.

[00:16:11]Um so it doesn't expand uh significantly on a hot day, which is exactly the situation we're in at the moment. Okay, all good so far.

[00:16:32]Let's move on. Right. Uh they've got a couple of pictures here um of uh two different houses and they've got uh some circuits. Now, I would say that if I was going to draw a power supply, I'd either be drawing it as a cell that looks like this, or you might have maybe a battery, which is a number of cells in series.

[00:16:56]Uh, the other thing about it is if you look at these components up here, the taller side is where it's positive, and the shorter side is negative. Okay?

[00:17:05]Okay. Now, sometimes that's labeled, sometimes it isn't, but that would help you uh decide which way conventional current is in that circuit. Um, so Matty says, uh, as answers to the first one, state the type of circuit seen in house A and house B. Correct. Yeah, basically this one here, uh, A is a series circuit and B is a parallel circuit. Uh, and often these simple bits of information you will be assessed on. there'll be easy marks available. We've got basically and this should really be a positive sign on that side of their battery is basically there's only going to be one way that the current is going to be going around this circuit and it goes through this followed by this followed by this. So there's a series of things one after each other. On this one here we've got parallel components. So this one's in parallel with that in parallel with that. So this is a parallel circuit. Right? When the lamps were purchased, the resistance of each lamp was included in the information booklet provided. Explain how the total resistance of the circuit and house a can be calculated. So, this question is basically about how do you calculate the resistance of a series circuit?

[00:18:17]Basically, um uh so the slow-mo, can we get a 67? No, that's not the answer yet.

[00:18:24]Maybe we'll do one later. Maybe we'll just have to wait for it like everybody does when they're waiting at McDonald's.

[00:18:29]Yeah, we're not going to get one of those just yet. Um, explain how the total resistance can be calculated uh by adding Oh, by adding together the resistance of each individual lamp.

[00:18:59]Okay. And basically this comes from the equation. Yeah. The suspense remains for for that for that number. Uh the total resistance RT would be equal to R1 + R2 + R3. So for example, imagine in this first one imagine that had a resistance of 10 ohms. That had a resistance of 8 ohms and that had a resistance of 12 ohms. The total resistance RT would be equal to this resistance 10 plus this one plus this one which is equal to 30 ohms. So this is really simple.

[00:19:33]Basically the more things you have in a line in series the greater the overall resistance. Okay. Um explain why the lamps in house A are dimmer than the lamps in house B. So again, this is saying why is it that um the lamps here are dimmer than these ones? And it's because let's let's put some numbers in. Um imagine we had a 6V supply here and we had a sixvt supply over there. So really low, but let's just imagine this is a simple DC circuit. That six volts is going to be shared between these three components.

[00:20:09]Whereas here, each of those components would have six volts across it. The other thing is that we've got a bigger overall resistance in this circuit here because what we have is a larger resistance and therefore we're going to have a smaller current. So we're going to have a small potential difference across each component and a small current going through it. And this then links to one of the equations that says the power or the energy transferred per unit time which is going to be related to how bright that bulb is is equal to VI.

[00:20:42]And if you've got a low value of potential difference, a low value of current, we're going to have a low power for each of the lamps here. In this circuit, there's going to be a much greater current going through each of these lamps, and there's going to be a much bigger potential difference across it, and therefore, these ones here are going to be brighter. So, the question says, explain why the lamps in house A are dimmer than the lamps in house B. So I guess as part of our answer uh we might say that um and maybe there's not enough space for a three mark answer. In reality if you had a three mark question in a GCSE paper you'd be given about half a page to explain it. Um would we ever be asked to explain how the resistors lower the current? Like you have to talk about electrons. Um I don't know. There might be something about maybe explaining why why does adding more why there might be a question asking maybe why is it if you add more resistors in the circuit it lowers the current you might say this increases the overall resistance of that circuit um but it's hard to know I think if you understand that electrons are having to kind of move around that circuit that's a really important kind of conceptual understanding of what electricity is anyway let's go back to this um In circuit A, um the potential difference is shared between the components or between the lamps.

[00:22:28]Uh and there is a lower current.

[00:22:36]Therefore, oh, sorry, that's more of an A level thing. Basically, three dots just means therefore. I'll write it out here. Uh, therefore, the power of each lamp is smaller uh than circuit B. Okay. So basically this comes from the fact that P is equal to VI. If you got a lower value of potential difference, a lower value of current across each or through each component, we're going to have a lower power. Okay.

[00:23:12]Um right. If a lamp breaks in house B, explain the effect if any on the other lamps in house B. So basically imagine this top one here was to break. All that would happen would be that that part of the circuit is affected and the other parts remain the same. So the other two lamps would stay lit. Whereas in circuit A, if one of these broke, that would be effectively like an open switch in the circuit, and that would mean that there couldn't be the electrons moving around the whole thing. So, um, explain the effect on the other lamps in house B.

[00:23:45]Uh, no effect.

[00:23:49]Um, they would stay lit lit up at the same brightness. Uh, and that's an advantage of having a parallel circuit. Um, yeah. Yeah. Cool. Uh, so slow-mo says there might be some emotional damage.

[00:24:15]Uh, but because they are wide and parallel, they will stubbornly keep shining through the trauma. I think you've got the right answer there, the slow-mo. I don't know how many marks they give that, but yeah, you're definitely Yeah, you're definitely right. Okay. Um, many domestic appliances such as lamps are designed with safety features to protect the user and their home. Explain one of these safety features. So, I guess we could maybe think about uh the earth wire.

[00:24:43]That's one of them. Uh, we might think about a fuse.

[00:24:47]Uh, we might think about a plastic casing.

[00:24:52]So, these are three things that we might consider. The earth wire means if there is a fault and you've got an AC circuit, that would mean any electricity rather than going through you, if there is a maybe short circuit inside, that would then go through the earth wire rather than through you. Um, a fuse is designed to stop something overheating. Um, because with a fuse, it's like a thin piece of wire that if the current's too big, it burns through the fuse wire and that stops a component working. Well, a plastic casing is an insulator, which means rather than touching a metal casing, you might touch a plastic casing. So, it's insulated from that.

[00:25:30]Um, so yeah, fuse, right? So, let's go for um let's go for the fuse. Um, the fuse will melt if the current is too large.

[00:25:52]Uh and then this stops uh the appliance overheating.

[00:26:02]Uh and a a kind of a subtle thing here to remember to realize is that the fuse it won't necessarily it won't necessarily stop an electric shock, but it stops the component getting too hot.

[00:26:15]Because what this is doing is if the current is too big, that's when we have these heating effects. And if the current is too big, then that's when the current can cause a heating effect. It might cause a fire. So the fuse is about stopping something overheating, whereas an earth wire is to stop you getting an electric shock. Um, people are asking some great questions. Will there be an Alevel physics paper two for uh or paper three? Yeah, I'm going to be doing one of these tomorrow for OCR paper 2 at 2 o'clock in the afternoon. I'll put all the times up in my kind of feed on YouTube as well. Uh I also put out in my newsletter. So about 10,000 people this morning were notified that I'm doing some Alevel classes tomorrow and Friday at 2:00 ready for paper two. Okay. Uh nice one. So we've got a bicycle pump.

[00:27:06]As a gas inside the pump is compressed, the metal pump becomes warm. State what happens to the pressure in the pump when the handle is lifted, assuming the temperature of the gas remains constant.

[00:27:19]Right. I think this I had a quick read through it before. I don't think this is a good question because what we talk about at GCSE is we can say that um if you've got something so let me just kind of write this down. So in terms of like the the model of gases, if you've got something at a constant volume, so the volume is a constant value, then you need to remember that the pressure is related to the temperature.

[00:27:51]So if you increase the temperature, we increase the pressure provided we've got a constant volume of something. The other thing you need to know about is something called Boil's law where this is about a constant temperature. So imagine you've got something at the same temperature. We can now say that the pressure times the volume is equal to a constant value. And what that means is that the pressure is equal to this constant K over V. Or we can say that the pressure is inversely proportional to the volume. So if you decrease the volume, we increase the pressure. If we increase the volume, then we decrease the pressure. But that's only true if you have a constant mass or a constant number of gas particles. Now the reality is if you've got a bicycle pump as you lift it up what it does is it pressure reduces slightly and that draws more air into it. So, as you push the handle up, this means that air is going to be basically rushing inside the pump, and we're going to have more gas particles introduced inside.

[00:29:02]And of course, when you push it down, these air particles then get pushed through this tube into the tire. So, I would say here that um state what happens to the pressure in the pump. You can just say it decreases.

[00:29:19]And that's enough to get you one mark because all we're doing here is we're stating what happens. It would either decrease, increase, or remain the same. Uh, now I'm going to say it decreases, but strictly speaking, this isn't um using this equation here because what we've actually got is a changing mass of gas inside that thing. So, I think it's not a very good question. If they said uh the pump if it was like um a pump that was sealed so no air could get in or out as you increase the volume the pressure would decrease. Um but I guess this strictly isn't a really good question I'd say. Uh yeah right. Explain why the pump gets warmer as a gas is compressed. In your answer refer to work done, pressure, and the energy transfer to the gas particles.

[00:30:10]So, we're going to have to think about what do we mean by work done? What do we mean by pressure? And then what about the energy transfer? So, there's a lot here. Yes, it's a six marker. Um, you will be getting a six marker. Um, but I would say don't feel that you have to use every single line here. What you can do, uh, and I think this is really important, I'm going to put it at the top, is, um, bullet points can really help you structure your answer and make sure that you're not spending too long writing.

[00:30:44]Okay, let me just get another sip of water.

[00:30:54]Okay, so um, sorry, my voice went a bit weird there. Yeah. Um I I appreciate that some people might get a bit of writer's block. Um let's just even if you don't get all the six marks, even if you just get three or four, that's going to be enough to get like a grade six or seven uh or seven, right? So um so why the pump gets warmer?

[00:31:16]So we can say that um work is done as a gas is compressed because a force is applied over a distance. Okay, so that's the first thing I'm going to say there. Uh, and so basically there's an equation that says the work done on an object is equal to the force times the distance. And here, imagine you've got this kind of plunger on that pump. As you're pushing it in over a distance, you're applying a force. So because we're applying I'm just going to underline this. We've got a force being applied over a distance and therefore work is done as that gas is compressed. uh and basically we can then say this means energy is transferred to the gas.

[00:32:28]So when you do work on something what we're doing is we are transferring energy from one place to another. And of course this energy what form is that or what kind of store is that going to be in? Uh we can therefore say that um that increases the kinetic energy of the gas particles uh so they move faster.

[00:33:09]So what we're doing is as we transfer energy to them, what kind of energy?

[00:33:13]Well, the kinetic energy store of the particles increases. And if they're they've got more energy, they're going to have the same mass, but they're now going to be moving faster. So we've got those kind of key ideas there. Um and of course, if you've got um things which have more kinetic energy, the kinetic energy of the particle is related to its temperature. Okay. So that means we can then say the temperature of the gas increases.

[00:33:46]So that's my next bullet point. So we're saying that the temperature of the gas increases because the temperature of something is related to how quickly the particles inside are moving around. And of course we also have um as uh so we've got um is that mode sub uh mode subdone um says more frequent collisions. Okay, that means we also have more frequent collisions and collisions with a greater force.

[00:34:33]Because if we've got something colliding with the walls quicker, there's going to be a greater change in momentum and therefore a greater force being applied.

[00:34:41]So more frequent collisions and collisions with a greater force uh result in a greater pressure of the gas.

[00:34:56]And basically pressure is um the pressure is going to be equal to the force divided by the area. So whatever the forces um from each collision of that molecule divided by the area of that side of that container. When you've got an increased force that means we're going to have an increased pressure of that gas. And we increase the force because we we've got things which are moving quicker. And also the rate of change of that momentum is going to increase because there's going to be more frequent collisions. Uh and therefore these kind of things here mean that we have a greater pressure of the gas. So what I've got there is a six mark answer that basically means um you can write in bullet points for my own kind of kind of sense check. What I did was I highlighted the key things I needed. Have I got work done in my answer? Yes, I do because I explained it there. Do I have pressure? I've got stuff about pressure down here. Do I have stuff about energy transfers? I do because I've got it here and I've got it here. So, I've basically made sure that everything the question is asking me to do I've got here. And I didn't even have to use the full piece of paper. So, don't feel for a six marker you have to fill up the whole page. Uh, somebody says this would probably get eight marks. Yeah. Um the when when we talk about collisions, what we're not talking about is a chemical reaction. Now, in a chemical reaction, you need to have a successful collision maybe between the different things that are going to be reacting together. So, you have more collisions and more successful collisions to make the reaction happen.

[00:36:32]Here, we just have collisions between particles and the side of that container that they're contained within. So, it's not so much we have a successful collision. It just means we have more collisions between the gas particles and the side of that container. So, if we think about what a model of the gas looks like, you've got the particles here.

[00:36:54]These are going to basically collide with the edge of the container. They're going to bounce back off. Uh, and the faster something is moving, the more rapidly it's going to be going side to side. There's going to be more collisions per second with the side of the container and there's going to be a bigger for bigger force. Right, there we go. That was that one there.

[00:37:13]Okay, 4.1.

[00:37:15]We've got a cube of material. It's got a mass of 500 g and a volume of 200 cm cubed. So, uh maybe just underline the key bits of data. So, we've got the mass here and the volume is a capital V that I've got over there. Now, that's been given in grams. That's been given in centimeters cubed. Okay. Calculate the density in kilograms per cubic meter.

[00:37:39]So, um what we need to do then uh somebody's asking about the rocket behind me. Yeah, this is my last creation. Um this one here is a Lego uh tintin rocket. It's not going on vintage. This one here is staying firmly in the office with all the other Lego behind me. Uh, but I think that this is like if you're talking about a rocket, this is like a proper rocket, isn't it? And also at the very top there's also um let's see if I can show this. At the very very top there's also here we go. You can actually see they've got the kind of little kind of capsule where uh the people would go to the moon in. So yeah, this is a proper rocket. This is so much more fun than like the big kind of like the big white ones and things like that.

[00:38:26]So yeah, that is proper rocket. Let me put it back.

[00:38:31]Um, yeah, there we go. Anyway, uh, got it mentioned. Yeah, it's a proper rocket. Um, okay. So, use the physics equation sheet as always. I'm going to write down that density is equal to mass divided by volume. So, density is this symbol here, which is called row. Uh, and that's the like a kind of curly slloy P kind of thing, but it's not a P, it's a row. Uh, so it's a Greek letter row. Little m for mass, big V for volume. Um, so the mass is equal to 500 g. So that's equal to 050 kg and we're going to divide that by 200 cm cubed. Now this is where we need to convert from cm into meters. So we can do that anywhere here. I'm just going to do it to the side. If you've got 1 cm, that's the same as 0.01 of a meter. Okay? If you had 1 cm squared, that would be equal to 0.01 m* 0.01 m, which is, let me just do this down here. So 01 * 01 is equal to 1 * 10 -4 m squared.

[00:39:58]Now if you had 1 cm cubed, that's the same as 0.01 multiplied by 0.01 multiplied by 0.01 m. So that's 01 * 01 * 01 which is 1 * 10 -6 m cubed. So basically what this means is if you had a cime cubed that would be 1 * 10 - 6. So if you've got 200 cm cubed, that would be 200 ultiplied by 1 * 10 - 6 or that's 200 * 10 - 6. And that's going to give us the number that we've got in m cubed, which is what we need to do. So that's going to be 0.5 / 200 * 10us 6. And for those of you who are kind of pretty up to speed on all your maths, you've done paper one, you've got paper two coming up. If you've got 200 * 10 - 6, that's going to be the same as 2 * 10 - 4, then we just do 0.5 divided by that answer is equal to 2,500.

[00:41:10]And of course, the units are going to be kilogram per cubic meter. So there we go. That is the density and that sounds about right. Um you might remember that water uh liquids like this have a density of about a th00and uh kilogram per cubic meter. This one here being uh metal might well be you know a lot more than that. So about two and a half times as dense as water.

[00:41:40]Okay.

[00:41:43]A substance changes from a liquid to a gas. Explain why the density decreases.

[00:41:49]Uh basically we can think about the equation that we had up here that says density is equal to the mass divided by the volume. Now if you've got something where we've got the same mass of particles but they all spread out that means the volume is going to increase the mass is going to stay the same and so the density must decrease. So yeah um so what we can say is that um as it uh turns from a liquid to a gas uh the same mass of particles occupies a larger volume uh so the density decreases that's basically it really I think um right yeah so um for the last question I've got a question there in the comments saying why did we divide by 200 * 10us 6. The reason being that we were given that in centime cubed, but we need to give something with the units of me cubed. Now there's basically um 1 cm cubed is quite small. If you think about it in reality, it's like literally this big. And if you had um a cube which was a meter by a meter by a meter, you'd have like 100 cubes along the bottom, 100 cubes that way, and 100 cubes in that dimension. So you basically get a million cubic in one meter cubed you'd have a million cm cubed. But of course we're going the other way. So basically we're we're looking at a millionth of a meter cubed is a cime cubed. And that's why I multiplied by 10 - 6. So I got the units in kilograms up here divided by meters cubed to give my final answer in kilograms per cubic meter. Okay. Um right uh what is meant by the specific latent heat of vaporization?

[00:44:14]I think this one might be a little bit more specific than is needed for GCSE.

[00:44:19]Basically there's the latent heat of fusion which is when a solid goes to a liquid and vaporization is as a liquid turns into a gas. So the specific latent heat of vaporization we could say this would be um the energy required uh to the energy required to um turn one kilogram of a liquid into 1 kilogram gram of a gas at a constant temperature.

[00:45:10]And so what we find is that when you've got a change of state from solid to liquid or liquid to solid or vice versa, as you change the state of that thing, it all happens at a constant temperature. Okay. Uh yeah. So somebody said the slow-mo says the energy needed to change the state at constant temperature. And it's also worth saying there that it's about a kilogram of something. In this case, going from a liquid to a gas at a constant temperature. Cool. Uh, dry ice changes directly from a gas into a solid. Name the process. So, this is like the weird one. Um, so normally we talk about melting, boiling, or freezing or condensing. This one here, the process of a solid going directly into a gas. We call that process uh sublimation.

[00:46:04]Uh and only a few things really do that at normal kind of uh temperature and pressure. So one of these uh correct uh says uh mode subun uh sublimation is a correct answer. That's going to get you one mark. Explain what happens to the energy and to the particle during this change in state. So, um, the particles I should probably write this in, yeah, I'm just going to write this in blue.

[00:46:30]The particles, um, gain kinetic energy or do they? I suppose during that change in state, actually, that's not true necessarily because the particles, if this happens at a constant temperature, their kinetic energy might stay the same. Um, the particles gain energy to break the bonds between them.

[00:47:11]The particles gain energy to break the bonds between them. Um, escaping the solid as a gas. That's not very well explained, but I can't see where there'd be four marks for a question like this.

[00:47:29]They are strong bonds. Uh yeah, so I guess um they're going to be strong bonds between the solids and the particle. Normally this happens like kind of two two phases, but I guess uh to break the strong bonds. So let's put that here. the strong bonds between them especi escaping the solid as they turn directly into a gas. Is it potential energy?

[00:47:52]Yeah. Um yeah, they gain potential energy. Sorry, your answers, by the way, in the chat are a lot better than mine.

[00:47:59]Um yeah. So yeah, uh AGS BVB. Yeah, the particles gain potential energy to break the strong bonds between them, escaping the solid as a gas. uh sublimation that's going to get you the marks.

[00:48:14]Oh my gosh, it is so hot in here.

[00:48:17]Right, this one here. Standard question here. Describe the model of the atom shown in figure 4. Uh we've basically got the plum pudding model.

[00:48:29]Uh plum pudding is basically like a Christmas pudding. Uh so you've got um a C of positive charge with embedded uh negative electrons.

[00:48:57]Basically that's what it is. So you've got this kind of unit this kind of sort this whole thing here is all kind of positive. Um and then what we've got embedded within this and throughout this is we have the electrons these smaller particles over here. Uh so this is a bit like raisins inside a Christmas pudding.

[00:49:16]Uh so somebody said ball of positive charge with negative electrons embedded within it. Perfect. Yeah. The plum pudding model and electrons embedded in the positively charged ball. Perfect.

[00:49:25]Yeah. So great stuff there um in the live chat at the moment. Really good.

[00:49:31]Explain what can cause electrons to shift between energy levels within an atom. So this is what happens. Uh we see that we can excite things. And of course as the electrons drop back down energy levels, they give out electromagnetic radiation. And that's the reason why when you do your flame tests and chemistry, different types of element will give out a different color of light. So copper is different to sodium which is different to burillium and all those other things like that. Um so uh what causes electrons to shift between uh energy levels within an atom? It's when they absorb or emit uh electro magnetic radiation.

[00:50:22]So it could be that you shine a light on an object, the light is absorbed by the electrons and they move up a level and as they drop back down they remit that light. Okay. Um, somebody's asking good questions. Why if the if light charges repel, why do protons stay together? Um, so basically this isn't individual positive things in the plum pudding model. So it's not like when they knew about this, they knew about protons. They basically said, let me just get something to explain that.

[00:51:15]So, so with the plum pudding model, imagine we've got like a ball of bluetac. Now, that's all positively charged. And what we have are these negative electrons which are embedded within this kind of positive thing. So it's not like we've got individual positive protons. We've just got this ball of positive charge and then we embed the negative electrons inside it.

[00:51:38]So that's very much what the plum pudding model is like. And then it was later when they did some other experiments that they found that actually we do have individual kind of positive charges in the middle um that kind of stick together in the nucleus.

[00:51:53]So here we've got maybe three positive charges here. Let me just make these a little bit better. Somebody hears Lego.

[00:51:59]Do you know what? I didn't have any Lego just there where I went to go and kind of sort that out. And now in the the the actual nucleus you've got positive charges which stick together. Now, of course, positive things do repel and they do attract these negative electrons towards it, but they attract the negative things, but everything's moving in a circular path. So, what we have is circular motion of electrons. So, even though there's this force of attraction between the two things, the electrons don't get sucked into the middle of that atom. Just like our sun is orbiting uh sorry just like our earth is orbiting the sun there's a force of attraction between the two things but we just keep moving in a circular path around it and there's actually another force inside uh called the well there's like the weak and the strong nuclear forces and basically the strong nuclear force is going to be something that actually overcomes their electrostatic repulsion but you'll learn more about that when you do Alevel physics next year So uh I guess nicely segueing into this bit here. Describe Bor's model of the atom. Uh basically uh Bor's model of the atom is that um uh what do we know? So we know that we've got um we got a positive nucleus with protons.

[00:53:27]Uh we've got uh shells of negative electrons uh that orbit this.

[00:53:44]Um and also electrons can exist in different shells or energy levels.

[00:54:00]Uh and that's basically kind of the main things we know about the bors model. Uh so basically this was based on hydrogen which is very simple because hydrogen is one proton and one electron and we could then describe the behavior of the electrons that we see around hydrogen the kind of spectra that they emit. Um and we can describe all of that with bor's model. This was before the new uh the neutron was discovered. So this was about 1911 1913 and it wasn't until about 20 years later in the 1930s that they actually discovered the neutron.

[00:54:30]So, Bor's model is basically a positive nucleus made out of protons and negative electrons in shells. Uh, and obviously the electrons can move between those.

[00:54:39]Okay. Heard it wasn't a boring model.

[00:54:42]Very good. So, it's a slow-mo, right?

[00:54:44]Um, what else could you What else have they got here? Uh, yeah, I guess of course uh inside the nucleus basically um the mass is concentrated uh in the nucleus um and therefore the atom is mostly empty space.

[00:55:16]So there we go. Uh all good standard stuff. So basically in the bore model we've basically got this dense positive nucleus where all the mass is concentrated. Then we've got mostly empty space and we've got electrons in shells.

[00:55:28]Explain why the overall charge of an atom is neutral. Um we can say that the number of positive protons is equal to the number of negative electrons.

[00:55:57]There we go. So, basically, we've got positive protons, we've got negative electrons, and the number is equal.

[00:56:04]Therefore, there's going to be no overall charge.

[00:56:08]There we go. Uh, that one there I thought was actually quite simple.

[00:56:12]Okay. Then we have a question which is a bit a bit more kind of like practical physics, but of course, a lot of this stuff here is going to be the same as the kind of skills that you've already learned for biology paper one and chemistry paper one. So it's just about doing an experiment looking at independent dependent control variables and so on. State two control variables in this experiment. So they've got 200 cm of hot water that's poured into identical beers. So I would say even just looking at this, we've got the same volume of water and we've got the same starting temperature. So what we could say that two control variables are the same volume of water.

[00:56:56]And you can see as well along this first row here at time t=0 they've got the same temperature um of water there. So also the same volume and the same starting temperature.

[00:57:10]Anything else I should have or could have put down.

[00:57:16]What else do we have? Um, somebody who says that they don't think this is a good reflection on the upcoming paper. They're very unlikely to ask that. Yeah, I agree. Define insulation. I don't think that's a key scientific term they need you to know the definition of. Um, but what else on this thing here could I add? What else is a control variable for this experiment? I guess we might have maybe the I don't know. It could be like you've got the same uh room temperature. So imagine uh the room is at 22 degrees.

[00:57:52]You'd want it to stay the same because you know if I was doing the experiment now at like the heat of the day at like kind of 3:00 in the afternoon, it's going to be much hotter than if I did it first thing in the morning when it's much cooler. So yeah, lots of things there that you could put down there.

[00:58:05]Define insulation. Uh basically what is what do we mean by insulation? Um, I don't think they'd Yeah, I think actually said in the chat, I don't think they'd ask this exact question. What do you mean by insulation? It's basically the It's like the kind of the resistance to the flow of heat energy. Um, so insulation is Yeah. Um, and I guess this is talking about thermal insulation.

[00:58:39]Um, definition how good a material is at reducing the rate of thermal energy transfer.

[00:59:03]So, a better insulator is going to be a better thing to slow down the rate of thermal energy being transferred through that material. I reckon that's that's good enough for that.

[00:59:15]Uh, compare the temperature change seen when using aluminum and when using no cover. So, we're looking at aluminium and no cover. So, I guess in the table, what we're looking at is this change here and no cover. So the rest of it is kind of irrelevant, but it's really worth just looking at exactly what we need to look at. And I suppose of course looking at the data, they start at the same temperature. This one falls down to 58 and that one falls down to 48. So if we're going to be comparing some data from the table as it says in the question, we need to maybe quote some of the numbers. So we could basically say that um when there was no cover um the temperature change was bigger.

[01:00:19]Uh and then for we can maybe say reducing to 48 degrees rather than 58° with the aluminium.

[01:00:41]So when there's no cover, the temperature change is greater, reducing to 48 degrees rather than 58 degrees with the aluminium. So I've kind of actually stated some numbers and things like that in this um calculate the average rate of temperature decrease per minute using the foam insulation. So when we talk about the word rate what we mean is per unit time like you'll have seen in chemistry where you might look at the the rate at which gas is produced uh in a chemical reaction for example. So when using foam insulation again just very clearly identify what you need to find and then with the foam which is this one over here we can see it goes from 80 down to 63. So the change in temperature which I'm going to call delta theta is equal to 80 minus 63 which is equal to 17° C. Now the rate if we're going to look at the decrease per minute uh so that's going to be the change in temperature over the change in time period is going to be equal to 17° over a time of 20 minutes. So that's 17 over 20. We could probably work this out in our head but we don't need to. We're just going to go straight to the calculator. That's equal to 0.85.

[01:02:04]So the rate is 0.85°. 85° per minute. So in 20 minutes it decreases by 17. So effectively that's the average rate. Although if we were to maybe look at the data, we'd probably see it starts off quicker and then the rate reduces as as time goes on. Um yeah. Okay. All good so far.

[01:02:28]Is everybody looking forward to next week? Oh yeah, by the way, let me know in the chat. I know there's a few people watching at the moment. Would you like me to do a mega revision session where I go through every single topic that could come up in paper one and just do like a mega revision session on Monday afternoon? Um, do people have exams Monday afternoon or is everybody going to be free at about 2:00? because I could do a 2:00 mega revision session, go through the specification point by point by point explaining every bit of the GCSE physics course specifically for AQA looking at paper one for like higher tier kind of students uh which also includes all the stuff that foundation tier students need to know. Um and yeah.

[01:03:07]No, no, that's good. Free people are free. Okay, this is good. Um also can you let me know in the chat are you doing AQA triple or are you doing trilogy? So triple science could include those who call it separate physics but basically can you let me know are you doing trilogy the combined science or are you doing triple science? Do let me know in the chat so I know what kind of thing to kind of focus these live sessions on.

[01:03:36]AQA triple uh says Mo Sabhan. You have a good day triple. Combined science says SDA. AGSBVB triple uh sound AA triple. Um yeah, basically somebody's doing trilogy. Yeah, basically most of this stuff here like 90% of it's common between trilogy and triple. So what I will do is on Monday then if I do this thing from 2:00 onwards then I will make it very clear what's for everybody during trilogy and what is only the triple content and that means that you can have a break or you just need to like don't don't do that.

[01:04:15]Um if you don't combined that's not a problem at all because again it's all it's all good revision right.

[01:04:22]Um so the next question is about specific heat capacity. Again the power supply well that's not again I draw this it might either be drawn as like a kind of electrical power supply like this or normally we have like a cell or a battery that looks like this. We've got a lid and therefore I guess this substance in here must be the assumption I'm going to make is that this is a liquid.

[01:04:51]So maybe we want to know the specific the specific heat capacity of some soup for example or some other kind of liquid. What is its SHC suggest why lid is uh used? Um we could say uh to reduce heat loss by evaporation.

[01:05:13]There we go. That's it. So we're reducing heat loss. You might have an insulated thing around the sides to stop the conduction, but the lid is going to stop that heat loss due to evaporation.

[01:05:25]So, they're the kind of things I'd be expecting in an answer. Right. The next bit suggests two precautions the students should take to obtain a high quality data.

[01:05:36]Uh, stir the water. Yeah. So what you want to have is you want to have an even temperature rise through the whole liquid through the whole substance. So therefore you need to talk about stirring the water.

[01:05:50]So stir the water uh before a temperature measurement is taken.

[01:06:04]Um precautions. I don't think that word is great. uh wait a bit before you take the temperature possibly. Um it might be that yeah within the first couple of seconds you don't get any rise at all but I think you'd account for that in in the graph that you draw. Uh stir the water before temperature. How do you tame high quality data? I think that GCSE questions it would be not two precautions but maybe take it might be suggest two uh procedures the student should take to obtain accurate data may might be the way that they might actually say this in the real exam. Um, so maybe it could be you use a digital thermometer uh that has been calibrated and that means you know it's going to give you a true value of what that temperature should be. Um, okay. During the experiment, the heater transfers 3 kg of energy to the beaker.

[01:07:20]Okay.

[01:07:25]H.

[01:07:34]Okay. I don't think this is a good question because it basically says it says the heater. Okay, so basically the heater is here and this isn't about the liquid, it's about the beaker. So this is basically about the energy loss in that experiment.

[01:07:53]And I think if it says that the heater transfers this amount of energy to the beaker, then the fact that the heater is 85% efficient is irrelevant because we've been told that that's the energy transferred to the beaker and we know the specific heat capacity of it and its mass. So the increase in temperature, we can use the equation that says E is equal to M C delta theta.

[01:08:22]And so let's put some numbers in. So the energy transferred is 3,000 JW. That's equal to the mass of 0.053 kg multiplied by 850 JW per kilogram per deg.

[01:08:43]So the reason being is if the we I'm going to discount that because this is more like it's not a good question and it's not been written that well. So therefore you I don't want to go into the details because I don't want to confuse people but basically it says here we know the energy transfer to the beaker. Now if the if the heater isn't efficient that inefficiency is going to be due to maybe the energy that goes into the liquid first of all. So what I'd say is 053 * 850 is 45.05. So 3,000 is equal to 45.05 times the change in temperature. And therefore 3,000 divided by this. So 3,00 / 45.05 is equal to our change in temperature which is 66.59.

[01:09:35]So that's about uh 67 degrees Celsius would be the answer um based on the amount of energy it's stated that's transferred to the beaker.

[01:09:48]Yeah. So this one here, don't worry about it. If you doing this at home, ignore question 7.3. It's not a clear question. Here we go. Six marker. Plan an investigation using the equipment shown and any other equipment needed to determine the specific heat capacity of the substance being heated. So this is what we need to know. Now first of all I'm just going to start with the equation that we'd use. The energy transferred is equal to m c delta theta.

[01:10:20]And the thing that we're trying to find out is little c. So how do we know the energy transferred? Well, that we know energy transferred is equal to power multiplied by time.

[01:10:33]And so we could say here instead that the power of the heater times the time which it's on for is equal to m c delta theta. But we also can work out power in an electrical circuit because power is equal to vi. So we could say that v * i * t is equal to m c delta theta. Okay, so this equation here is probably the most complicated equation that you will probably ever see in GCSE physics. What this means though is we need to use the following bits of equipment. So if you want to measure the potential difference, we need to use a voltmeter.

[01:11:14]So that's going to allow us to measure the value of V. If you want to measure the current, we're going to use an ammeter to measure the current. And then we're going to use a stopwatch to measure the time. To record the mass of something, we need to have a mass balance or a set of scales. And that's going to allow us to measure the mass of the object or the liquid that we're heating up. And to measure the change in temperature, we need a thermometer.

[01:11:46]Thermometer. There we go. So, we need a thermometer to measure that change in temperature. So, thinking about what we're going to do, that's the equipment we're going to be using. Uh, you also need to think about the voltmeter.

[01:11:59]By the way, this is not a kind of good answer. This is just me kind of going through the things and talking through it. The voltmeter needs to go in parallel with the heater, and that's going to measure the potential difference across it. And the ammeter needs to go in series with the heater. And that's going to allow us then to look at the current through it. And basically if you know the voltage which should the the potential difference which should remain the same you multiply that by the current which remains the same that will then give you the information you need to work this out.

[01:12:34]What you could then do is you could plot a graph [snorts] where if you were to plot data and you were to look at the change in temperature and you looked at the time, you should get a graph that will probably do something like this.

[01:12:53]Okay. Now, occasionally there's a bit of a time lag at the beginning when you turn the heater on and it takes a while for that thermal energy to be transferred from the heater over to the thermometer. Okay? So, there might be a time lag over here. What you then do is you work out for the straight part of the graph, you're going to be drawing in a grade uh a big triangle here. And this allows you to work out the gradient of that line. Because what you're going to be doing every time you do this, you're going to be get getting some data over several minutes and you're going to be plotting this line of best fit that has a straight line up here. And you want to know the gradient of that line. Now the gradient, by the way, I can see that number the current number of users has kind of decreased. But this is an important thing to remember. The current sorry the gradient is equal to our change in temperature divided by time. So the gradient is going to be the rate at which the temperature of that thing increases. So that's going to be d delta theta / delta t. And if we look at this equation up here, we can see that V * I over M is equal to C * delta theta / T.

[01:14:21]So what this means is that this thing here delta theta / T is going to be equal to the gradient.

[01:14:30]And so what that means is if you want to work out the value of C, what you need to look at is the value of V, you multiply that by the value of I and then you divide that by the value of the mass. And then what you do is you divide all of that by the gradient of that line. And that's going to then equal the specific heat capacity, which is C. Okay, there we go. Um, yeah, Alevel ED XL. Somebody wants me to do that, I'm doing an Alevel ED XL master class on Sunday afternoon at 4:30. All you need to do is go to Alevel physics online and book that uh on my classes page and then you'll be able to come along for a 2-hour master class. Uh, if you're asking for that, he patel. Yeah, basically I'll be there for you doing a paper two master class for edexl Sunday at 4:30.

[01:15:32]Cool. Right, there we go. That's basically the process. And of course, if you had this in a real GCSE paper, you just need to work through it step by step. Outline the equipment, how it's set up, what you're taking measurements for, what you might plot on a graph, and so on.

[01:15:49]Okay. Um, this one here I think is like a repeat of the previous question looking at the atomic model. So, um, what's the experiment that we've got here? What does that look like? A level and GCSE people watching the stream, all of you know what this is. Uh, so let's see what you're putting in the chat.

[01:16:11]Okay, so there's a couple of different names for it.

[01:16:20]So, one of these it could be sometimes known as the alpha scattering experiment.

[01:16:32]Uh the other one is it could also be called um the the Rutherford's uh gold leaf experiment. Both of these are correct.

[01:16:47]Basically, what we have in the middle here, we have a thin sheet of uh gold foil and then what we have are alpha particles which are basically fired towards it and then it scatters the alpha particles. Most of them go straight through. Some are deflected a small amount and some are deflected by more than 90 degrees. So yeah, alpha scattering says uh mode subun. Yeah, explain why most alpha particles pass through the gold foil. This is because uh the atom is mostly empty space.

[01:17:25]Um yeah, basically that's it. The atom is mostly empty space um with a small dense nucleus.

[01:17:41]Okay. Mostly empty space. Perfect. AGS BVB. Cool. Good stuff. That one there.

[01:17:47]Nice start to that question. Uh, a smoke detector contains 20 gram of amarissium 241, an alpha emitter with a halfife of 432 years. Calculate the mass of the original radioactive nuclei remaining after 864 years.

[01:18:05]So basically, well, I mean, I don't think anybody's expecting a smoke detector to last for that long, but this question comes back to looking at what happens to the number of nuclei over time in a radioactive sample. Now, this is going to fall to half its original amount. So, whatever that value is, we're going to half that.

[01:18:28]And that's basically this point here, which is this point down here. Now this point here when half of the original number have decayed is called the halflife. I'm going to call that t a half. And imagine this example here. So we start with 20 g. So maybe let's not think about the number of nuclei but maybe the mass of radioactive nuclei. We start with 20 g. After one half life we have 10 g left which is going to be 432 years. Now after another half life, we started with 10, but half of those 10 will have decayed. So we've now got five grams left after two half lives, which is going to be 864 years. And therefore, basically it halves and it halves again.

[01:19:15]So calculate the mass of the radioactive nuclei remaining after 864 years. We're basically we've got two half lives.

[01:19:28]Uh, and therefore we start with 20 grams and we're going to divide by two and then we're going to divide by two again which is basically the same as 20 / 2 ^ 2 which is equal to 20 over 4 which is just 5 g.

[01:19:46]There we go. Easy, simple.

[01:19:50]A scientist is running an experiment using radiation. It needs to be able to pass through the body.

[01:19:58]be detected outside the body and cause minimal damage to the body. Explain which type of radiation a scientist needs to use. So uh right we could either have alpha, beta or gamma. Uh and basically gamma would be most suitable.

[01:20:21]So that's going to get you one mark. But of course what we need to do is explain why. Uh basically that means we can then think about two features. How penetrating it is and how ionizing. It's basically uh the most penetrating and the least ionizing.

[01:20:48]So what we find is that alpha because it's quite large, it has very low penetrating ability. So things like skin can stop it. And even beta, these high-speed electrons, they will penetrate through some human flesh, but not all the way through. So if you had this inside you, your body would stop all the alpha and beta coming out, but the gamma would be able to get outside your body. It's also going to be the least ionizing, so it's going to be the least dangerous to you as well. So yeah, least ionizing. Excellent stuff like that. Another person asking about AQA.

[01:21:18]Um, I'm going to go through AQA ale physics paper 2. I'm doing a predicted paper at two o'clock on Friday. Doing that live. And also I'm doing my master class at 1:30 getting everybody ready for paper 2 AQA that you can book on my website.

[01:21:34]Yeah, there we go. We're almost done.

[01:21:38]Using figure seven, find the halflife of this sample. So it starts at 1600.

[01:21:45]I'm going to use a set square and a pencil. So we want to find when it goes down to 800 and so starts at 60 and goes down to 800 and therefore thinking about this and thinking about this that's got a time equal uh to 10 minutes.

[01:22:08]There we go. So whatever the original number was we've gone for half that. And this is a tricky graph because they didn't start at zero. They started at 200.

[01:22:17]Uh and this is all for paper one. Uh buzzfeed. Yeah, good. So it's paper one.

[01:22:23]Um using figure seven, calculate the percentage decrease in the number of nuclei in the sample between 5 minutes and 20 minutes. So this one is just like a GCSE math question. So at 5 minutes, I'm going to just put the set square there and we're going to draw off this number here, whatever that is. And then we've got 20 minutes. So this is going to be equal to this number here.

[01:22:47]Okay. So, what's that number? I guess midway between the two is going to be like,00.

[01:22:57]So, basically if if we look at the um let's look at the number at 5 minutes that's about,0040 and the number at 20 minutes is about 400. So the change in number so the change in that number is going to be 1140 minus 400 which is 740 and we're going to compare that to the number that we had originally. So that's going to be over 1140.

[01:23:36]Is that right?

[01:23:46]Um, is that right? 65 64.9 is about 65% decrease because we've decreased 1140 by about 65% to get 400 at the end.

[01:24:12]Yeah, that one there. This question here is just a math question in a physics concept.

[01:24:18]Um, okay then. Right, let's do this one. So, a car engine contains moving parts that rub against each other. Oil is added to the engine. explain how adding oil reduces energy waste in the engine. Uh so oil is a lubricant.

[01:24:40]So that's the first thing. Maybe one mark there. Uh this means this decreases friction.

[01:24:51]So um less work is done by forces in the engine.

[01:25:10]Uh so less energy is wasted as thermal energy.

[01:25:23]That's basically it really. So you oil something up, there's going to be less friction between the moving parts. If you got less friction, then less work is done over a distance. So there's going to be less work done uh against those frictional forces and that means less energy is going to be wasted by the engine.

[01:25:38]uh explain how double glazing reduces energy loss from the house. So um uh the double glazing um has an air gap or sometimes they use an insulating gas like argon. So the double glazing has an air gap um between panes of glass and basically air is a good insulator because gas is a good insulators because the particles are far apart. So air is a good insulator. Um uh so the rate of heat transfer decreases.

[01:26:40]There we go. That's it. 9.2.

[01:26:44]Oh my god, I'm so hot. My office is absolutely roasting. I've got a fan here that I don't know if you can hear it or not, but it seems to be having absolutely no effect on me. Uh, homeowner is considering adding solar panels to their house. Describe one advantage and one disadvantage. Do not refer to cost in your answer. So, let's do an advantage. So, what do you reckon it is? Um, what is an advantage of using solar panels and what is a disadvantage?

[01:27:17]I just put plus or minus in your answers. Uh what do you reckon some of the pros and cons are? Um I guess on a day like today, solar panels would be amazing because it's so sunny. Uh and that means there's a lot of daylight during the whole day and there's very little cloud cover. So we're going to be generating a lot of electricity on a day like today. So what kind of things do people think? So um let's have a think about this. One advantage could be that um uh weather dependent. It has a low efficiency so lots of lands need needs to be used. Um solar energy is renewable minus it's not always sunny says kois T5T. Yeah. So, a lot of these things, um, first of all, there's, yeah, you need a certain size of roof to actually fit them, and they won't necessarily be able to provide all the energy you need.

[01:28:12]So, they might not have a really high efficiency. They might only be like 20% efficient. So, yeah. Um, so it could be that an advantage could be that, uh, solar is renewable or let's say solar is Yeah. renewable.

[01:28:30]Or you could say um no CO2 emitted when they're working. There might be a small amount of CO2 maybe uh when they're being produced. Uh yes, so it does not release carbon dioxide. That's good. Um a negative might be uh dependent on the weather.

[01:28:53]Um therefore you need to have a backup.

[01:28:55]You still need to be connected to the national grid. Uh but yeah, some good answers there. Um, cool. So, dependent on weather. Uh, what else could we say?

[01:29:04]Um, doesn't work at night.

[01:29:12]Uh, or maybe even the roof may not be suitable.

[01:29:22]Right. The next one, state one, environmental impact of extracting fossil fuels. So this one here, we've got to have an environmental impact. Uh great if you're doing geography, but it's all about the extracting fossil fuels. So it's not about actually burning them. So what could be an impact? Uh and you might be thinking about either coal, oil, or natural gas.

[01:29:44]They're the main fossil fuels that we talk about. So what could be one of the impacts uh on extracting these? And again, this is where you might think about what you've seen in the news recently, the kind of things that might come up every so often. You might hear about disasters. uh you might think about uh pollution in other countries around the world or other parts of the world. So again interesting to see what people might say uh releases carbon dioxide which contributes to global warming.

[01:30:16]I think you got to be very careful when you talk about CO2 is it you might it might be for example that in order to to mine coal or to drill for oil there's going to be CO2 that's used in that process. You got to be very careful that carbon dioxide isn't seen as what's released when they're burnt. Um so I think you need to be very careful about how the extraction process uses up or releases carbon dioxide. Uh, I suppose something else we might talk about is um there could be an oil spill.

[01:30:51]Um, and this might affect marine life.

[01:30:56]So, think about what happens if you've got a big oil tanker that's transporting uh a load of natural oil or natural gas maybe or oil in it. Maybe there's a disaster at sea. That oil slick spreads on the water and affects seabirds and things. Habitat destruction is a great one as well because in order to um build a coal mine, you're going to have to be like digging into the ground that's going to affect the habitat of anything around it. Yeah. So, it could be habitat. There's lots of things in here.

[01:31:21]Um but of course, the key thing here is when it says state one in your answer, just put down one thing here.

[01:31:30]Yeah. Right. Okay. Um number 10. A scientist is studying different types of carbon. why these atoms are described as isotopes. Uh so this is basically what is the definition of an isotope. So it's got uh the same number of protons but a different number of neutrons.

[01:32:07]So all of these things have six carbon atoms. So there' be 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6. Um but they have a different number of neutrons. Now carbon 12 has six protons and six neutrons. So there's 12 things in total in the nucleus. Carbon 13 has an extra neutron and carbon 14 has two extra neutrons.

[01:32:31]Now the neutrons don't affect its chemical properties. They're going to have the same number of electrons. all of these things. So they're chemically they behave the same, but because they've got a different structure to their nucleus, they're going to be unstable by a different amount. Um, yeah. So Razie the one says, uh, sorry, Risy says they have the same number of protons, six, but a different number of neutrons. Excellent. Yeah, good answer there.

[01:32:56]A nuclear power station uses uranium fuel rods to generate electricity.

[01:33:00]explain how a chain reaction is produced in nuclear fishision and why it must be carefully controlled within the power station. Uh basically um we can say that as uranium splits apart it releases neutrons which uh go on to be absorbed.

[01:33:36]So as uranium splits apart, it releases neutrons which go on to be absorbed by other uranium nuclei which then split apart releasing energy. This could easily be like a six mark question this one uh releasing energy. Uh and basically they release energy um with the kinetic energy of all of the particles that come off. So the daughter nuclei the two smaller things that uh that the uranium splits into and it gives out two or three or four neutrons depending on exactly what happens. But of course these neutrons are absorbed by other uranium things. They then become unstable. They split apart and the kind of process goes on. Um, and of course what you want is one reaction to cause one reaction to cause one reaction. So you have this controlled chain reaction that's critical. Um, and it's controlled by control rods.

[01:34:43]So a uh so a chain reaction occurs.

[01:34:54]Yeah. So basically controlled by control rods. So a chain reaction occurs and this basically absorbs any excess neutrons. So we have there might be three neutrons released. We want to absorb two of those. So that one of those neutrons is absorbed by one more uranium. That might emit three neutrons.

[01:35:11]We absorb a couple of those to leave one left that can be absorbed by another one and so on. Uh boron control rods. Yes.

[01:35:17]Uh if you want to, you can state what these are made out of. But I think at GCSE you just keep it fairly generic.

[01:35:24]You don't need to be too specific about things like what the moderator is made out of, about the coolant water, about what the control rods are made out of.

[01:35:32]So just keep it fairly generic. I would say that this is much more likely to be like a six mark question than a three mark question. And then finally uh figure eight shows two processes state two differences between the processes.

[01:35:46]Um uh okay fish is when large nuclei split apart.

[01:36:06]But fusion is small nuclei joining together.

[01:36:20]So I think that's one big difference. Um as uh Ricey says fusion occurs between smaller nuclei. Um what's the other difference is uh fusion only occurs at high temperatures high temperatures and pressures. So for example here fusion can only occur in either like an experimental fusion reactor or in the center of something really big like a star whereas fishision can happen at a much lower temperature. So therefore it's much easier to control that. Uh fish requires a neutron for a chain reaction to take place. Yeah that's something else. Yeah. So it might be that um in order to start fishing you need to have a neutron that's absorbed by this and then of course it makes these two things and it makes some more neutrons which are given out as well. So uh you might talk about how fishision if it's induced nuclear fishision it needs to absorb a neutron first whereas these things here don't need to absorb a neutron for them to react but you do need to have these at high pressures and high temperatures. high temperatures, high pressures means you can have collisions that actually take place. Um, but yeah, there we go. That was the end of that paper. Um, if you want to find more stuff like this, I do have my practice papers. So, uh, I do have these for papers one, two, and three. In total, I've got three practice papers.

[01:37:59]Uh, no, I've got six practice papers.

[01:38:01]Sorry. Um, for paper one, I drew that.

[01:38:05]That took me ages to draw a solar panel like that. Uh, another question here kind of similar to this one about uh cubes of different density. Um, I've got uh questions about electrical circuits, all sorts of bits and pieces here. Um, there's another one here looking at radioactive decay. So, I've got uh six practice papers that I've got. Um, you can find these in my shop. Uh, there's a link to that in the description. Um, but basically, a lot of people wanted me to do another live stream. I know people might watch this afterwards, but I'll be doing another live stream. uh in preparation for GCSE physics paper one.

[01:38:41]I'll be doing that Monday afternoon from 2 o'clock. I suspect that's when people start to panic. But until then, I'm going to be doing lots more A-level stuff uh including um more predicted papers for AQA physics, um OCR physics.

[01:38:54]I'm doing a capacitor thing Saturday morning and I'm doing workshops on Sunday. So hopefully see all of you there if you are uh Alevel students.

[01:39:02]Apart from that though, thank you everybody uh in the chat. Great to see everybody there today. Um, and if you want to find more help and support over the coming days, just head over to GCSE Physics online where I've got everything laid out for you as you're working hard towards your exams.