Question

A constant net torque is applied to an object. Which one of the following will NOT be constant?

Answer 1

Answer:

B) Angular velocity

Explanation:

The equivalent of Newton's second law for the rotational motions can be written as:

$\tau = I \alpha$

where

$\tau$ is the net torque applied to the object

I is the moment of inertia

$\alpha$ is the angular acceleration

From the formula we see that when a constant net torque $\tau$ is applied, then the object also has a constant angular acceleration, $\alpha$.

But we also know that

$\alpha = \frac{d\omega}{dt}$

where $\omega$ is the angular velocity: so, a constant angular acceleration means that the angular velocity of the object is changing, so the correct answer is

B) Angular velocity

(moment of inertia and center of gravity do not change since they only depend on the mass and the geometry/shape of the object, which do not change)