A solid disk with a radius of $7 m$ and mass of $12 kg$ is rotating on a frictionless surface. If $120 W$ of power is used to increase the disk's rate of rotation, what torque is applied when the disk is rotating at $15 Hz$ ?

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Answer 1 · 2018-03-28T06:00:39

The torque is $=1.27Nm$

Apply the equation

$"Power (W)" ="torque(Nm)"xx"angular velocity" (rad s^-1)$

The power is $P=120W$

The frequency is $f=15Hz$

The angular velocity is

$omega=2pif=2xxpixx15=(30pi)rads^-1$

Therefore,

The torque is

$tau=P/omega=120/(30pi)=1.27Nm$

A solid disk with a radius of 7 m7 m and mass of 12 kg12 kg is rotating on a frictionless surface. If 120 W120 W of power is used to increase the disk's rate of rotation, what torque is applied when the disk is rotating at 15 Hz15 Hz?