# What is the moment of inertia of a pendulum with a mass of 4 kg that is 3 m from the pivot?

May 28, 2018

$I = 36 k g \cdot {m}^{2}$

#### Explanation:

The typical pendulum's "bob" is size is much smaller than the length of the pendulum shaft. Assuming that to be the case here, the mass is a point mass, and the moment of inertia is given by

$I = M \cdot {R}^{2}$

Therefore, $I = 4 k g \cdot {\left(3 m\right)}^{2} = 36 k g \cdot {m}^{2}$

I hope this helps,
Steve