A solid disk with a radius of #5 m# and mass of #3 kg# is rotating on a frictionless surface. If #72 W# of power is used to increase the disk's rate of rotation, what torque is applied when the disk is rotating at #4 Hz#?

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Answer 1 · 2017-07-28T06:13:10

The torque is #=2.86Nm#

The mass of the disc is #m=3 kg#

The radius of the disc is #r=5m#

The power and the torque are related by the formula

#P=tau omega#

The angular velocity is #omega=2pif=2pi*4=8pirads^-1#

The power is #P=72W#

Therefore,

The torque is

#tau=P/omega=72/(8pi)=2.86Nm#