An object with a mass of 3kg is traveling in a circular path of a radius of 2m. If the object's angular velocity changes from 1Hz to 3Hz in 5s, what torque was applied to the object?

1 Answer
Jan 4, 2016

=60.75N.m.

Explanation:

From rotational dynamics we get that τ=Iα, where τ is the torque, I is the moment of inertia, and α is the angular acceleration.

But since angular acceleration is the rate of change in angular velocity, we get that α=dωdt.

We then first need to convert the linear frequency in Hertz into angular frequency in rad/s.

α=dωdt=(3×2πr)(1×2πr)5=5.0265rad/s2.

Moment of inertia I=jmjr2perpj=mr2dm.

So in this case for a point mass, I=mr2=3×22=12kg.m2.

Therefore resultant torque is τ=Iα

=12×5.0265

=60.75N.m.