An object with a mass of # 8 kg# is traveling in a circular path of a radius of #12 m#. If the object's angular velocity changes from # 15 Hz# to # 4 Hz# in # 5 s#, what torque was applied to the object?

1 Answer
Sep 19, 2017

The torque was #=15924.1Nm#

Explanation:

The torque is the rate of change of angular momentum

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

where #I# is the moment of inertia

The mass of the object is #m=8kg#

The radius is #r=12m#

For the object, #I=mr^2#

So, #I=8*(12)^2=1152kgm^2#

And the rate of change of angular velocity is

#(d omega)/dt=(Deltaomega)/t=(30pi-8pi)/5=22/5pirads^-2#

So,

The torque is

#tau=1152*22/5pi=15924.1Nm#