Question

Question: A constant net torque is exerted on an object. Which of the following quantities for the object cannot be constant? Choose all that apply. (a) angular position (b) angular velocity (c) angular acceleration (d) moment of inertia (e) kinetic energy

Short answer

Answer

The quantities that cannot be constant if a constant net torque is exerted on an object are:

1. Angular position
2. Angular velocity
3. Kinetic energy.

Step-by-step solution

Defining torque 

Torque is defined as a measure of force that can cause an object to rotate about an axis. Torque is what causes an object to acquire angular acceleration. It is a vector quantity.

The magnitude of torque ‘ $\mathit{\tau }$’produced by a force’F’is given by

$\mathit{\tau }\mathbf{=}\mathit{F}\mathbf{·}\mathit{r}\mathit{s}\mathit{i}\mathit{n}\mathit{\theta }$

where

‘ r’ is the length of the moment arm

‘ $\mathit{\theta }$’ is the angle between the force vector and the moment arm.

Defining the quantities that cannot be constant when constant net torque is exerted on an object

Angular velocity: This will change at a rate equal to the torque.

Angular position: If the angular velocity changes, the angular position will also change.

Kinetic energy: When a torque is applied, the linear or angular speed changes at a rate proportional to the torque. So the kinetic energy will also change.