# An object with a mass of  3 kg is traveling in a circular path of a radius of 7 m. If the object's angular velocity changes from  3 Hz to  7 Hz in 3 s, what torque was applied to the object?

Jul 17, 2017

We will use cassical mechanics (rotation) equations to solve this problem.

#### Explanation:

With frequency of $3 H z$ the velocity is ω_1=2pif_1=6pi(rads)/s

With frequency of $7 H z$ the velocity is ω_2=2pif_2=14pi(rads)/s

The angular acceleration is then

α=(Δω)/(Δt)=(14pi-6pi)/3=(8pi)/3(rads)/s^2

and the torque is :

Τ=Iα=mr^2α=3*49*(8pi)/3=392piNm