Motion in one dimension

1. Introduction

• In our dialy life ,we see lots of things moving around for example car passing through from one place to other ,person riding on a bicycle and many more like this.
• In scientific terms an object is said to be in motion ,if it changes its position with the pasage of time and if it does not change it position with the passage of time then it is said to be at rest
• Both the motion and rest are relative terms for example mobile kept on the table is resting at its position but it is moving in the sense as earth is rotating on its axis.So for a person seeing mobile from earth it is at rest and for person on moon earth seems to change its position with time and so mobile is moving.
• Simplest case of motion is rectilinear motion which is the motion of the object in a straight line
• In our descriotion of object ,we will treat the object as an point object
• Object under consideration can be treated as point object if the size of the object is much smaller than the distance travelled by it in a reasonable time duration for example length of a motor car travelling a distance of 500km can be neglected w.r.t distance travelled by it.
• Here in kinematics ,we study ways to describe the motion without going into the cause of the motion

2. Position and Displacement

Question:

A particle is thrown vertically upwards. It reaches the height H and the come downward.What is the distance and displacement in the whole motion?

Question:

True and False Statement

a) Distance is a Vector quantity?
b) Displacement is a Vector quantity?
c) Dimension of Distance and displacement are same?
d) Displacement on round trip is zero?

3. Average velocity and speed

Question:

A car moves a distance 100 km in 2 hours. What is the average speed of the car?

Question:

A man moves from his residence to market and return back to residence in 2 hours. The distance between market and residence is 20 km.

a) what is average velocity of the man?

b) what is the average speed of the man?

Question:

True and False Statement

a) Average speed is a scalar quantity?
b) Velocity is a Vector quantity?
c) Dimension of Velocity is LT-1?

4. Acceleration

Question:

A car moves in a straight road. The velocity at point A is 50 km/hr, It presses the accelerator paddle and reach point B in 10 sec. The velocity ar point B is 100Km/hr

Find the average acceleration of the car from point A to point B?

Question:

True and False Statement

a) Acceleration is a scalar quantity?
b) if the velocity of the object is zero,then acceleration will always be zero?
c) Instantanous speed is always equal to magnitude of instantaous velocity

5. Relative velocity

Question:

A ball is dropped vertically from a height h above the ground .It hits the ground and bounces up vertically to a height h/2.Neglecting subsequent motion and air resistance ,its velocity v varies with the height h as

Question 2. The displacement -time graph of a moving particle is shown below.The instantanous velocity of the particle is negative at the point

a. C
b. D
c. E
d. B

Question 3. The velocity -time graph of a moving particle is shown below.Total displacement of the particle during the time interval when there is nonzero acceleration and retardation is

a. 60m
b. 40m
c. 50m
d. 30m

Question 4. Figure below shows the displacement -time graph of two particles.Mark the correct statement about their relative velocity

a. It first increases and then decreases
b. It is a non zero constant
c. it is zero
d. none of the aboveQuestion

Question 5. What all graph shows motion with positive velocities
a. a and c only
b. all the four
c. b and D only
d. b only

Question 6. What all graph shows motion with negative velocities
a. a and b only
b. all the four
c. a and c only
d. c only

Question 7. Which of the folliwing graph correctly represents velocity-time relationships for a particle released from rest to fall under gravity.

Question 8. The v-x graph of a particle moving along a straight line is shown below.Which of the below graph shows a-x graph