What is rotational inertia?

Rotational inertia, also known as the moment of inertia, refers to an object's reluctance to rotate about an axis. It quantifies how much torque is needed for a desired angular acceleration around a rotational axis. The greater the rotational inertia, the more torque is required to change the object's angular velocity. This concept applies to various physical scenarios, such as how a heavy object or one distributed further from its axis of rotation is harder to rotate compared to a lighter object or one concentrated closer to the axis.

Understanding rotational inertia is essential for fields such as physics and engineering, as it influences how objects move in a rotational manner. It is foundational for analyzing physical activities, including sports and exercise, as it can impact performance, technique, and safety. The other choices pertain to different concepts, such as dynamics and motion but do not accurately describe the specific nature of rotational inertia.