# An object with a mass of  3 kg is traveling in a circular path of a radius of 3 m. If the object's angular velocity changes from  4 Hz to  7 Hz in  8 s, what torque was applied to the object?

Nov 11, 2017

$\text{63.6 Nm}$ of torque was applied to object.

#### Explanation:

Torque is rate of change of angular momentum.

T = (I(omega_f - ω_i))/t

$= \frac{I 2 \pi \left({f}_{f} - {f}_{i}\right)}{t}$

$= \frac{m {r}^{2} 2 \pi \left({f}_{f} - {f}_{i}\right)}{t}$

= ("3 kg × (3 m)"^2 × 2 π (7 - 4) "Hz")/"8 s" = "63.6 Nm"