Question

A particle is tied to one end of a light inextensible string and is moved in a vertical circle, the other end of the string is fixed at the centre. Then for a complete motion in a circle, which is correct.

(air resistance is negligible).

• A. Acceleration of the particle is directed towards the centre
• B. Total mechanical energy of the particle and earth remains constant
• C. Tension in the string remains constant
• D. Acceleration of the particle remains constant

Answer 1

The correct option is B Total mechanical energy of the particle and earth remains constant

At any time force acting on particle vary and hence acceleration (net) will have different direction at different times. Tension also changes and its minimum at top point. Magnitude of acceleration also varies.

Considering earth and particle as a system and no external force on system is acting, total mechanical energy will be conserved.