Mechanical Engineering Principles

152 MECHANICAL ENGINEERING PRINCIPLES

12. Which of the following statements is
    false?

(a) An externally applied force is

needed to change the direction of

a moving object.

(b) For every force, there is an equal

and opposite reaction force.

(c) A body travelling at a constant

velocity in a circle has no accel-

eration.

(d) Centripetal acceleration acts to-

wards the centre of the circle of

motion.

13. An angular acceleration of 10 rad/s^2
    occurs when a circular disc of mass
    moment of inertia of 0.5 kg m^2 is
    subjected to a torque. The value of the
    torque is:

(a)25Nm (b)5Nm

(c) 20 N m (d) 0.05 N m