Question

A solid disk with a radius of `2 m` and mass of `2 kg` is rotating on a frictionless surface. If `15 W` of power is used to increase the disk's rate of rotation, what torque is applied when the disk is rotating at `1 Hz`?

Answer 1

The torque is `=2.39Nm`

Explanation:

mass of disc `=2kg`

radius of disc `=2m`

The power is related to the torque by the equation

`P=tau *omega`

`P=15W`

Frequency of rotation is `f=1Hz`

`omega=f*2pi`

angular velocity, `omega=1*2pi rads^-1`

torque, `tau=P/omega`

`=15/(2pi)=2.39Nm`