An object with a mass of # 2 kg# is traveling in a circular path of a radius of #4 m#. If the object's angular velocity changes from # 2 Hz# to # 4 Hz# in # 3 s#, what torque was applied to the object?

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Answer 1 · 2017-04-28T05:38:28

The torque was #=134Nm#

The torque is the rate of change of angular momentum

#tau=(dL)/dt=(d(Iomega))/dt=I(domega)/dt#

The moment of inertiai is #=I#

For the object, #I=(mr^2)#

So, #I=2*(4)^2=32kgm^2#

The rate of change of angular velocity is

#(domega)/dt=(4-2)/3*2pi#

#=(4/3pi) rads^(-2)#

So the torque is #tau=32*(4/3pi) Nm=134Nm#