Question

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

(a) a point on the rim,

(b) the middle point of a radius.

Answer 1

Given in the question

Angular speed, ω = 20 rad/s

r = 10 cm = 0.10 m

Now for condition (a)

Here, The linear speed at rim = ωr

=ωr

= 20 x 0.10

= 2 m/s

Now for condition(b)

At radius middle point 

r' = 0.10/ 2 

r' = 0.05 m

Hence

The linear speed at middle point radius = ωr'

= 20 x 0.05

= 1 m/s .