A solid disk with a radius of #3 m# and mass of #4 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 #12 Hz#?

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Answer 1 · 2017-07-02T06:35:41

The torque is #=1.59Nm#

The mass of the disc is #m=4 kg#

The radius of the disc is #r=3m#

The power and the torque are related by the formula

#P=tau omega#

The angular velocity is #omega=2pif=2pi*12=24pirads^-1#

The power is #P=120W#

Therefore,

The torque is

#tau=P/omega=120/(24pi)=1.59Nm#