sdgfasdgf

Added: 2026-05-10

[00:00:00]You are welcome to my scholars. This is Sameer.

[00:00:03]We are studying class nine science chapter eight motion.

[00:00:09]Motion means that in our everyday life we see some objects are at rest.

[00:00:14]Whereas other are in motion.

[00:00:17]Birds are flying, fishes swim, blood flows through winds and arteries.

[00:00:23]And car moves.

[00:00:27]Atoms, molecules, planets and stars and galaxies all are in motion.

[00:00:37]We often perceive an object to be in motion when its position is changing with respect to time. The position of this car is being changed with respect to time. So this car, red one, is in motion. Whereas the white one is stationary, is in a stationary condition.

[00:01:00]However, there are situations where the motion is inferred through indirect evidence.

[00:01:14]For example, we infer the motion of air by observing the movement of dust and movement of leaves and branches of the tree.

[00:01:26]Like we are observing that there is air by the movement of this paper. This paper is moving. This shows that the air is moving around us.

[00:01:38]What causes the phenomena of sunrise, sunset and changing of season?

[00:01:45]It is also due to the motion of the earth.

[00:01:50]If it is true, why don't we directly perceive the motion of the earth?

[00:01:55]We cannot perceive the motion of the Earth, since we are living on the Earth.

[00:01:59]An object may appear to be moving for one person and a stationary for some other.

[00:02:06]For the passengers in a moving bus, the roadside trees appear to be moving backward.

[00:02:16]A person is standing on the roadside perceives the bus along with the passengers as moving.

[00:02:26]However, a passenger inside the bus sees his fellow passengers to be addressed.

[00:02:36]Most motions are complex. Some objects may move in a straight line, like this car white is moving in a straight line.

[00:02:49]Other may take a circular path.

[00:02:52]Like this red one is moving at in a circular path.

[00:03:03]Some may rotate.

[00:03:05]Like you can see the wheel of this car is rotating.

[00:03:10]Rotating on its axis.

[00:03:20]A few other examples.

[00:03:22]Some objects vibrate, like this pen is vibrating.

[00:03:28]This is known as vibration. Means that it is changing its position through its mean position. Sometime it is going right, then left, then mean position, then right, then mean position again, then left.

[00:03:43]So, there may be situation involving a combination of these.

[00:03:51]We shall first learn to describe the motion of objects along a straight line.

[00:03:58]We shall also learn to express such motions through simple equation and graph later.

[00:04:07]We shall discuss way of describing circular motion also.

[00:04:15]So, now we are studying describing motion.

[00:04:21]We describe the location of an object by specifying a reference point. Suppose there is a car.

[00:04:29]It is moving.

[00:04:30]So, it is changing its position with a specified point. Suppose we can say there is written science. So, it is changing its position with respect to science what it is written.

[00:04:43]Or we can say it is changing its position with respect to this cap. It is changing now the position with respect to this cap. So, this cap of the pen is a reference point for the moving car.

[00:05:02]Let us assume another situation that a school in a village is 2 km north of the railway station. We have a specified the position of the school with respect to the railway station.

[00:05:17]In this example, the railway station is known as the reference point. So, for the car, this is the reference point. We can say the word science is written from this reference point.

[00:05:35]3 cm 3 cm upward.

[00:05:41]This way we have a specified the position of the object.

[00:05:48]We could have also choose other reference point according to our convenience.

[00:05:53]As we have chosen this cap reference point for the science and for ninth class for learning made simpler for my scholars, we may also choose another point of reference like this is star and this uh class ninth what it is written.

[00:06:10]Therefore, to describe the position of an object, we need to specify a reference point.

[00:06:17]Suppose we want to specify the position of this cap. So, this cap is placed below the word science written.

[00:06:31]Motion along a straight line.

[00:06:35]The simple type of motion is the motion along a straight line.

[00:06:41]We shall first learn to describe this by an example.

[00:06:45]Consider the motion of an object along say motion of this car along a straight line.

[00:07:02]The object it starts its journey.

[00:07:08]Suppose there is a ruler and this object, the car, is starting its journey.

[00:07:21]So, the object it starts its journey from A and reaches to C and then reach to B and then A comes back to C, comes back to O.

[00:07:38]So, this way >> Let A, B, and C represent the position of the object at different instance.

[00:07:52]At first, the object moves as I showed you through C and B and reaches at A.

[00:08:00]This car moves through C, B, and reached at A. Then it moves back along the same path and reach at C through B.

[00:08:12]So, the total length covered by the object in this case the is killed marked according to the scale is marked the total path length covered by the object is O A.

[00:08:30]It is O A plus O A plus A C A C and then to B. That is 60 km plus 35 km is equal to 95 km.

[00:08:51]This is the distance covered by the object. To describe the distance, we need to specify only the numerical value and not the direction of the motion.

[00:09:04]There are certain quantities which are described by specifying only their only their magnitude.

[00:09:16]So, the objects which we describe by only their magnitude are known as a scalar quantity.

[00:09:25]For this For this example, can you find out the distance of the final position C of the object from the initial position O?

[00:09:35]This reference will give you the numerical value of the displacement of the object from O to C through A.

[00:09:46]O to C through A back through A.

[00:09:56]So, the shortest distance measured from the initial to the final position of an object is known as the displacement. In this case, when the car moved from O went to C, then B, then A, and came back to O, the displacement is zero.

[00:10:20]Because we compare the displacement of an object from the point of starting point.

[00:10:30]From for motion of the object from O to A, the distance covered in first case is 60 km as the object went from O and reached at A, the distance covered by 60 km.

[00:10:48]And the magnitude of displacement is 60 km during its motion from O to A and back to B.

[00:10:58]O to A and back to B the distance covered is equal to 60 km 60 km and then 25 km.

[00:11:10]60 km plus 25 km means the total 85 km. But, the displacement will be 35 km.

[00:11:21]The displacement will be 35 km.

[00:11:25]So, this way the distance covered is 85 km and the displace >> This little light of mine, is this little light of mine, I'm going to let it shine.

[00:14:14]Everywhere I go, I'm going to let it shine.

[00:14:56]Everywhere I go, I'm going to and you in this bliss land by by all souls no man meaning peace seeking as meaning when we join when two souls become he knew he had three missed turns from home back.

[00:17:57]And then he And then he And then he And then he And three And then he And then all >> Release >> [snorts] >> a little shiver.

[00:20:05]I can't bear to look at the white face of the moon.

[00:20:45]I can't look at the white face of the moon.

[00:21:17]slow fire and is I and as and share around and and >> [snorts] >> and and >> Fear.

[00:23:57]So is the meaning the word and the word that is written written is equal to the is just [snorts] me father for I have sinned.

[00:25:18]Yeah.

[00:25:31]It >> [snorts] >> has been four years and four months since my last e- or It has been four years and six she love Bless me she love she love she love she love one three from all the eight six teen millions six teen millions >> [music] >> he >> [snorts] >> had from eight >> [music] >> two all >> I mean sleep >> [music] >> sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep >> [snorts] >> sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep sleep >> Yes.

[00:30:46]And this this this man I knew knew this right the old worker knew she and now she and look into the bright memory we can can with the dress the dress the dress the Amen.

[00:32:44]Amen.

[00:33:04]Amen.

[00:33:17]Amen.

[00:33:19]Amen.

[00:33:21]Amen.

[00:33:29]Amen.

[00:33:30]>> [sighs] >> Amen.

[00:34:10]Amen.

[00:34:12]Amen.

[00:34:14]Amen.

[00:34:15]Amen.

[00:34:26]Amen.

[00:34:30]Amen.

[00:34:33]Amen.

[00:34:39]leaving you.

[00:34:49]We shouldn't have stayed that traveling made you >> [music] >> fall in love with him.

[00:35:46]I'm leaving you.

[00:35:57]My love