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#### Motion Book Back Questions

9th Standard

Reg.No. :
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Science

Time : 00:45:00 Hrs
Total Marks : 30
4 x 1 = 4
1. Slope of the velocity - time graph gives

(a)

speed

(b)

displacement

(c)

distance

(d)

acceleration

2. A car is being driven at a speed of 20 ms-1 when brakes are applied to bring it to rest in 5 s. The decelaration produced in this case will be

(a)

+4 ms-2

(b)

‒4 ms-2

(c)

‒0.25 ms-2

(d)

+0.25 ms-2

3. Which one of the following is most likely not a case of uniform circular motion?

(a)

Motion of the Earth around the Sun

(b)

Motion of a toy train on a circular track

(c)

Motion of a racing car on a circular track.

(d)

Motion of hours hand on the dial of the clock

4. The force responsible for drying of clothes in a washing machine is

(a)

Centripetal force

(b)

Centrifugal force

(c)

Gravitational force

(d)

Electro static force

5. 4 x 1 = 4
6. Speed is a ____________ quantity whereas velocity is a ____________ quantity

()

scalar, vector

7. The slope of the distance – time graph at any point gives __________

()

the constant speed

8. Consider an object is rest at position x = 20m. Then its displacement – time graph will be straight line to _____________ the axis.

()

Parallel to

9. Negative acceleration is called ____________

()

retardation

10. 4 x 1 = 4
11. The motion of a city bus in a heavy traffic road is an example for uniform motion

(a) True
(b) False
12. Acceleration can get negative value also.

(a) True
(b) False
13. Distance covered by a particle never becomes zero between any interval of time but displacement becomes zero

(a) True
(b) False
14. The velocity – time graph of a particle falling freely under gravity would be straight line parallel to the x axis

(a) True
(b) False
15. 2 x 2 = 4
16. Mark the correct choice as:
(a) Both assertion and reason are true and reason in the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.
Assertion: The accelerated motion of an object may be due to change in magnitude of velocity or direction or both of them.
Reason: Acceleration can be produced only by change in magnitude of the velocity it does not depend the direction.

17. Mark the correct choice as:
(a) Both assertion and reason are true and reason in the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.
Assertion: Displacement of a body may be zero when distance travelled by it is not zero.
Reason: The displacement is the shortest distance 'between initial and final position.

18. 3 x 3 = 9
19. An object travels 16m in 4s and then another 16m in 2 s. What is the average speed of the object?

20. Surya swims in a 90 m long pool. He covers 180m in 60 s by swimming from one end to the other and back along the same straight path. Find the average speed and the average velocity of Surya.

21. A 900 kg car moving at 10 ms-1 takes a turn around a circle with a radius of 25 m. Determine the acceleration and the net force acting upon the car.

22. 1 x 5 = 5
23. The following graph shows the motion of a car. What do you infer from the graph along OA and AB? What is the speed of the car along AB and what time it reached this speed.