Question

A turntable rotates at 45 r.p.m. What is it's angular speed?

Answer 1

A turntable rotates at `45 r.p.m` means, it takes `1 m` to complete `45` rotations,

So,time taken to complete `1` rotation is `1/45 *60 s=1.34s`

This is the time period(`T`) (by definition)

So,angular speed= `omega = (2pi)/T = (2pi)/1.34=4.7 (rad) /s`