Newton's Second Law of Motion, Class 9 Science

1. The S.I. unit of force is

Newton-metre

Newton

Newton per second

Newton per square metre

Question 1 of 20

2. Two balls A and B, of masses m and 2m are in motion with velocities 2v and v respectively. Compare the force needed to stop them in the same time.

2 : 1

1 : 2

1 : 1

None of the above

Question 2 of 20

3. Find the time taken by a body of mass 16 kg to come to rest from a uniform velocity of magnitude 10 m/s, when a force of 4N is applied continously

20 s

30 s

40 s

50 s

Question 3 of 20

4. If the force acting on the body is zero. Its momentum is:

Zero

Constant

Infinite

None of the above

Question 4 of 20

5. Which of the following has the largest momentum?

A cat running down the street

A pickup truck travelling down the highway.

A large truck parked in a parking lot.

A car parked in a parking lot.

Question 5 of 20

6. What force can change the velocity of a body of mass 1kg from 20 m/s to 30m/s in two seconds?

10 N

15 N

5 N

25 N

Question 6 of 20

7. Find the time for which a force of 1kgwt acts on a body of mass 1 kg moving with a uniform speed of 4m/s to stop the body.

0.8 s

0.2 s

0.6 s

0.4 s

Question 7 of 20

8. A resistive force of 16 N acts on a ball of mass 40 g continuously. If the initial velocity of the ball is 24 ms^-1 ,the time taken by it to come to rest is:

0.04 s

0.08 s

0.06 s

0.02 s

Question 8 of 20

9. The acceleration of an object is inversely proportional to:

Force.

Momentum.

Mass.

Velocity.

Question 9 of 20

10. Quantitative expression of force is given by:

Newton’s second law of motion.

Newton’s third law of motion.

Newton’s first law of motion.

Newton’s law of gravitation.

Question 10 of 20

11. If the same force acts on two bodies of different masses which are initially at rest and gain same displacement, then the ratio of time for which these forces act is:

Question 11 of 20

12. A man throws a ball weighing 200 g vertically upwards with a speed of 10m/s. Its momentum at the highest point of its flight will be:

2 kg. m/s

2000 kg.m/s

Insufficient data to find the momentum.

zero.

Question 12 of 20

13. In high jump competition the athlete is made to fall on a cushioned bed to:

To decrease his momentum fast.

Make him stop quickly.

Increase the time to stop.

Make him sleep comfortably.

Question 13 of 20

14. Which of the following is the relation between SI unit of gravitational force and Newton?

1 kg wt = 9.8 N

1 kg m s^-2 = 1 N

1 N = 10⁵ dynes

1 dyne = 1 g cm s^-2

Question 14 of 20

15. A carpenter exerts a force of magnitude 1.5 N at right angles to the surface of a nail of mass 3 gram to drive it into the wood. If wood offers a resistive force of 0.6 N and the time of interaction of hammer and the nail 0.01 s, the depth through which the nail penetrates is:

15m

1.5 cm

15 cm

1.5 mm

Question 15 of 20

16. Change in momentum when a car weighing 700kg changes its speed from 100m/s to 200 m/s is:

14000 kg.m/s

10500000 kg.m/s

21000000 kg.m/s

70000 kg.m/s

Question 16 of 20

17. Momentum of a body of mass 0.5 kg moving with a speed of 10 m/s is

2.5 kg.m/s

5 kg.m/s

0.5 kg.m/s

50 kg.m/s

Question 17 of 20

18. The relation between acceleration, mass and force is given by:

a x F = m

F = m/a

F x m = a

a = F/m

Question 18 of 20

19. What is the momentum of a body of mass 2m and velocity v/2?

mv/4

2mv

mv/2

Question 19 of 20

20. An object of mass 20 kg is moving with a velocity of 10 m/s. Its momentum will be:

2000 kg.m/s

20 kg.m/s

2 kg.m/s

200 kg.m/s

Question 20 of 20