JEE Main Physics: Kinematics Quiz Set 1

1. A body moves a distance of 80 meters in the first 2 seconds and then travels an additional 100 meters in the next 4 seconds while decelerating. What is the velocity of the body at the end of the 5th second?

5 m/s

25 m/s

20 m/s

40 m/s

Explanation

2. An object starts from rest and travels a distance 3D with uniform acceleration, then moves a distance 4D with uniform velocity and finally comes to rest after moving a distance of 5D under uniform retardation. What is the ratio of the average velocity to maximum velocity?

1/3

3/5

4/7

8/9

The area of velocity – time graph represents the Displacement:

Explanation

The area of velocity – time graph represents the Displacement:

3. A body is released from top of a tower of height X m. After 1 s, the body I stopped and then instantaneously released. What will be its height (from the ground) after next 2 s? (take g = 10 m/s²)

(X - 5)

(X - 25)

(X - 20)

(X - 40)

Explanation

4. Going from city A to city B, a car accelerates uniformly from rest, then moves with constant velocity, and finally retards uniformly. If the ratio of time taken is 1:6:1 and the maximum speed is 80 km h^-1, Then what is the average speed over the journey?

Explanation

5. A heavy stone is dropped into a well in which the water level is at depth H below the ground level. If the speed of the sound is 'v' then the time after which the splash is heard will be given by

The time in which the sound of splash will be heard is equal to the total of the time taken by the stone to reach the water level & the time taken by the sound to come out of the well

Explanation

The time in which the sound of splash will be heard is equal to the total of the time taken by the stone to reach the water level & the time taken by the sound to come out of the well

6. An object is released from the top of a tower. Which of the following statement is correct about the time taken by the particle in falling through the successive distance of 1 m each?

All will be equal

None of These

Time taken by an object falling under gravity is given by to cover first n meter:

Time taken by an object falling under gravity is given by to cover first (n+1) meter: y

So time taken by the object falling under gravity is given by to cover (n + 1)^th meter:

So the required ratio will be:

Explanation

Time taken by an object falling under gravity is given by to cover first n meter:

Time taken by an object falling under gravity is given by to cover first (n+1) meter: y

So time taken by the object falling under gravity is given by to cover (n + 1)^th meter:

So the required ratio will be:

7. The height of a container is 1.5 m is being lifted up by a crane, with an acceleration of 2 m/s². One second after the start, a bolt from the roof of the container starts falling. What will be the displacement of the bolt before touching the floor of the container?

3/5

3/8

2/3

1/4

From the diagram it is clear that when the ball has reached the floor of the elevator, some upward distance has been travelled by the elevator as well. The ball is falling under gravity whereas the lift has the acceleration ‘a’. The displacement of the ball X = H – X’. The ball is moving in the opposite direction of elevator then the displacement = – X = – (H – X’). At the time of release of ball let the velocity of elevator was v₀ and at time T ball touches the floor of the elevator.

For the motion of ball:

Explanation

From the diagram it is clear that when the ball has reached the floor of the elevator, some upward distance has been travelled by the elevator as well. The ball is falling under gravity whereas the lift has the acceleration ‘a’. The displacement of the ball X = H – X’. The ball is moving in the opposite direction of elevator then the displacement = – X = – (H – X’). At the time of release of ball let the velocity of elevator was v₀ and at time T ball touches the floor of the elevator.

For the motion of ball:

8. A ball is released from the top of a tower. Another ball is released from a point 'H₂' meter below the top when the first ball has descended 'H₁' meter from the top. If booth ball are released from rest and reach the ground simultaneously then what is the height of the tower?

Explanation

9. An object starts sliding from the top of a triangular box with a base of 15 inches and a height of 8 inches. The Inclined height of the box is divided into three parts in such a way that the object takes equal times to slide down these parts. What will be the length of these parts?

15/9, 5, 75/9

20/9, 60/9, 100/9

17/9, 51/9, 85/9

10/9, 30/9, 50/9

Explanation

10. A passenger is standing on the platform. The passenger is standing at the beginning of the fourth coach of a train. How many coaches are there on the train if it takes 6 seconds by the fourth coach and 24 seconds by the rest of the train (including 4^th coach) to cross the passenger, then how many coaches are there in the train?

13

18

15

17

On solving these two equations we will get n = 13.

Explanation

On solving these two equations we will get n = 13.