# Engineering Mechanics – Section 4

11. The velocity ratio for the second system of pulleys is n.

A. True
B. False

12. The law of motion involved in the recoil of the gun is

A. Newton’s first law of motion
B. Newton’s second law of motion
C. Newton’s third law of motion
D. none of these

Correct Answer: C. Newton’s third law of motion

13. When a particle moves along a circular path, its acceleration has two components, one is normal component and the other is tangential component of acceleration.

A. True
B. False

14. A machine which is not capable of doing any work in the reversed direction, after the effort is removed, is called a reversible machine.

A. True
B. False

15. The range of projectile will be maximum for a given velocity of the projectile when the angle of projection (α) is

A. β/2
B. 30° + β/2
C. 45° + β/2
D. 60° + β/2

Correct Answer: C. 45° + β/2

16. When two elastic bodies collide with each other,

A. the two bodies will momentarily come to rest after the collision
B. the two bodies tend to compress and deform at the surface of the contact
C. the two bodies begin to regain their original shape
D. all of the above

Correct Answer: D. all of the above

17. The centre of gravity of a triangle lies at a point where its medians intersect each other.

A. True
B. False

18. In order to double the period of simple pendulum, the length of the string should be

A. halved
B. doubled

19. The moment of inertia of a square of side an about its base is a4/ 3

A. True
B. False