Question

If v is the velocity of the bob, the force that is responsible for decrease of amplitude is proportional to 

(a) v²  (b)  v  (c)  1/v (d)   1/v²

Answer 1

Correct option  (b) v

Explanation:

The bob of simple pendulum is spherical. When the pendulum is oscillating in air, it comes across resistive force offered by air known as viscous drag.

The viscous drag acting on a spherical object is given by empirical relation

Here η: coefficient of viscosity (constant) 

 v : speed of the object

r : radius of the sphere