Engineering Mechanics – Section 1

1. According to the principle of conservation of energy, the total momentum of a system of masses in any direction remains constant unless acted upon by an external force in that direction.

A. True
B. False

Correct Answer: B. False

2. The friction experienced by a body, when in motion, is known as

A. rolling friction
B. dynamic friction
C. limiting friction
D. static friction

Correct Answer: B. dynamic friction

3. Two balls of equal mass and of perfectly elastic material are lying on the floor. One of the ball with velocity v is made to strike the second ball. Both the balls after impact will move with a velocity

A. v
B. v/2
C. v/4
D. v/8

Correct Answer: B. v/2

4. The term ‘force’ may be defined as an agent which produces or tends to produce, destroys or tends to destroy motion.

A. Agree
B. Disagree

Correct Answer: A. Agree

5. The coefficient of restitution for elastic bodies is one.

A. Correct
B. Incorrect

Correct Answer: B. Incorrect
Answer Explanation:

The Coefficient of restitution for elastic bodies is 0 – 1.
The coefficient of restitution for perfect elastic bodies is 1.

6. The velocity ratio in case of an inclined plane inclined at angle θ to the horizontal and weight being pulled up the inclined plane by vertical effort is

A. sin θ
B. cos θ
C. tan θ
D. cosec θ

Correct Answer: A.sin θ

7. The range of projectile on a downward inclined plane is __________ the range on the upward inclined plane for the same velocity of projection and angle of projection.

A. less than
B. more than
C. equal to

Correct Answer: B. more than

8. The angle of inclination of a vehicle when moving along a circular path __________ upon its mass.

A. depends
B. does not depend

Correct Answer: B. does not depend

9. A body of weight W is required to move up on a rough inclined plane whose angle of inclination with the horizontal is α. The effort applied parallel to the plane is given by(where μ = tanφ = Coefficient of friction between the plane and the body.)

A. P = W tanα
B. P = W tan(α + φ)
C. P = W (sinα + μcosα)
D. P = W (cosα + μsinα)

Correct Answer: C. P = W (sinα + μcosα)

10. If the resultant of two equal forces have the same magnitude as either of the forces, then the angle between the two forces is

A. 30°
B. 60°
C. 90°
D. 120°

Correct Answer: D. 120°

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