Question

A solid disk with a radius of `5 m` and mass of `3 kg` is rotating on a frictionless surface. If `45 W` of power is used to increase the disk's rate of rotation, what torque is applied when the disk is rotating at `5 Hz`?

Answer 1

The torque is `=1.43Nm`

Explanation:

Mass of disc `=3kg`

Radius of disc `=5m`

The power is related to the torque by the equation

`P=tau *omega`

`P=45W`

Frequency of rotation is `f=5Hz`

`omega=f*2pi`

angular velocity, `omega=5*2pi rads^-1`

torque, `tau=P/omega`

`=45/(10pi)=1.43Nm`