What is needed to change the motion of an object?

To change the motion of an object, a force is required. According to Newton's Second Law of Motion, force is defined as the mass of an object multiplied by its acceleration (F = ma). This means that any change in the speed or direction of an object's movement necessitates the application of force.

For example, if you want to stop a rolling ball, you must apply a force in the opposite direction of its motion. Similarly, to get an object moving from rest, a force must be exerted to overcome its inertia. This principle emphasizes the role of force as the fundamental interaction that alters the state of motion of an object.

While energy may be involved in the context of performing work or moving an object, it is the application of force that directly causes a change in motion. Mass refers to the amount of matter in an object, and work is a measure of energy transfer when a force is applied along a distance, but neither mass nor work alone can change motion without the application of force.