A solid disk with a radius of #9 m# and mass of #4 kg# is rotating on a frictionless surface. If #640 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 · 2017-05-05T08:24:11

The torque is #=6.79Nm#

Mass of disc #=4kg#

Radius of disc #=9m#

The power is related to the torque by the equation

#P=tau *omega#

#P=640W#

Frequency of rotation is #f=15Hz#

#omega=f*2pi#

angular velocity, #omega=15*2pi rads^-1#

torque, #tau=P/omega#

#=640/(30pi)=6.79Nm#