Question

A disc of radius 10 cm is rotating about its axis at an angular speed of 20 rad/s. Find the linear speed of

(a) a point on the rim,

(b) the middle point of a radius.

Answer 1

Radius of disc = 10 cm = 0.1 m

Angular velocity = 20 rad/s

$\therefore$ Linear velocity on the rim = $\omega r=20\times 0.1=2\text{m/s}$

$\therefore$ Linear velocity at the middle of radius = $\frac{\omega r}{2}=20\times \left(\frac{\left(0.1\right)}{2}\right)$ =

$=1\text{m/s}$