# Multiple choice questions (MCQ) on Mechanics

1. The rate of doing work is known as

a. Potential energy        b. Power           c. Kinetic energy           d. None of the above

2. The moment of inertia of solid cone of mass ‘m’ and radius ‘r’ about its vertical axis is

a. 3mr2/10         b. 2mr2/10         c. 3mr2/5           d. 2mr2/5

3. Coefficient of friction is

a. The friction force acting when the body is in motion                      b. Ratio of limiting friction and normal reaction

c. The friction force acting when the body is just about to move         d. None of the above

4. Which of the following statement is correct?

a. The K.E. of a body remains constant

b. The K.E. of a body before impact is more than the K.E. of a body after impact

c. The K.E. of a body before impact is less than the K.E. of a body after impact

5. The maximum frictional force which comes into play, when a body just begins to slide over the surface of the other body, is known as

a. Limiting friction          b. Static friction

c. Dynamic friction        d. None of the above

6. The point through which the whole weight of the body acts, irrespective of its position is known as

a. Centre of gravity        b. Centre of mass

c. Moment of Inertia      d. None of the above

7. The total energy possessed by a system of moving bodies

a. Is constant at every instant                                         b. Varies from point to point

c. Is maximum in the start and minimum at the end          d. None of the above

8. If two bodies having masses m1 and m2 (m1˃m2), having equal kinetic energies, the momentum of body having mass m1 is _____the momentum of body having mass m2.

a. Equal            b. Greater than              c. Less than                  d. None of the above

9. Two like parallel forces are acting at a distance of 24 mm apart and their resultant is 20 N. If the line of action of the resultant is 6 mm from any given force, the two forces are

a. 15 N and 5 N             b. 20 N and 5 N

c. 15 N and 15 N           d. None of the above

10. When a person opens a door, he applies

a. Force            b. Torque          c. Moment        d. None of the above

11. An elevator weighing 10,000 kgf attains an upward velocity of 4m/s in two seconds with uniform acceleration. The tension in the cable will be approximately.

a. 8,000 kgf                  b. 10,000 kgf                c. 12,000 kgf                 d. 20,000 kgf

12. A ball is projected vertically upwards with a certain velocity. It takes 40 seconds for its upward journey. The time taken for its downward journey is

a. 10 s              b. 20 s              c. 30 s              d. 40 s

13. A spring of stiffness 100 N/M is stretched initially by 10cm from the undeformed position. The work required to stretch it by another 10 cm is.

a. 5 Nm             b. 7 Nm                        c. 10 Nm           d. 15 Nm

14. A truck weighing 150kN and travelling at 2m/sec impacts with a buffer spring which compresses 1.25 cm per 10kN. The maximum compression of the spring is

a. 20.00 cm                   b. 22.85 cm                   c. 27.66 cm                   d. 30.00 cm

15. Two forces A and B are acting at an angle θ. Their resultant ‘R’ will make an angle a with the force A, such that cosθ is equal to

a. (A+Bsinθ)/(A2+B2-2ABcosθ)1/2                                   b. Bsinθ/(A2+B2+2ABcosθ)1/2

c. (A+Bcosθ)/(A2+B2+2ABcosθ)1/2                                             d. Bcosθ)/(A2+B2-2ABcosθ)1/2

16. The motion of a particle (distance in metres and time in seconds) is given by the equation s=2t3+3t

Starting from t=0, to attain a velocity of 9m/s, the particle will have to travel a distance of

a. 5 m               b. 10 m c. 15 m             d. 20 m

17. The escape velocity from the surface of the earth is approximately equal to

a. 9.81 km/s                  b. 11.2 km/s                  c. 14.0 km/s                  d. 22.0 km/s

18. The springs of a chest expander are 60 cm long when unstretched. Their stiffness is 10 N/mm. The work done in stretching them to 100 cm is

a. 600 Nm                     b. 800 Nm                     c. 1000 Nm                   d. 1600 Nm

19. If the momentum of a given particle is doubled, then its kinetic energy will be

a. doubled                    b. quadrupled               c. halved                       d. unaffected

20. A bullet is fired vertically upwards from a rifle, with a velocity of 110 m/s, from the top of a 115 m high tower. If g=10m/s2, the velocity with which the bullet will strike the ground is

a. 220 m/s                     b. 175 m/s                    c. 120 m/s                     d. 115 m/s