# A solid disk with a radius of 9 m and mass of 2 kg is rotating on a frictionless surface. If 480 W of power is used to increase the disk's rate of rotation, what torque is applied when the disk is rotating at 15 Hz?

Feb 25, 2017

The torque is $= 5.1 N m$

#### Explanation:

The power is related to the torque, by the equation

$P = \tau \omega$

$P =$ power

$\tau =$ torque

$\omega =$ angular velocity

$P = 480 W$

$\omega = 15 \cdot 2 \pi = \left(30 \pi\right) r a {\mathrm{ds}}^{-} 1$

$\tau = \frac{480}{30 \pi} = 5.1 N m$