A solid disk with a radius of #6 m# and mass of #2 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 #9 Hz#?

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Answer 1 · 2017-05-05T06:15:19

The torque is #=2.12Nm#

Mass of disc #=2kg#

Radius of disc #=6m#

The power is related to the torque by the equation

#P=tau *omega#

#P=120W#

Frequency of rotation is #f=9Hz#

#omega=f*2pi#

angular velocity, #omega=9*2pi rads^-1#

torque, #tau=P/omega#

#=120/(18pi)=2.12Nm#