What is the definition of impulse in physics?

Impulse in physics is defined as the change in momentum of an object when a force is applied over a certain time period. This relationship can be expressed mathematically as impulse equaling the force applied multiplied by the time duration over which the force acts, which also corresponds to the change in momentum of the object. When a force is applied to an object, it alters the object's velocity, resulting in a change in momentum. Therefore, impulse is fundamentally linked to both force and the resulting change in momentum, making the correct answer clear.

The other options, while related to physics, do not correctly define impulse. Force applied over time is a part of the impulse-momentum theorem, but it is not the definition of impulse itself. Change in energy refers to different concepts in mechanics and does not encompass the specific relationship defined by impulse. Speed multiplied by time gives distance, which is unrelated to the concept of impulse. Understanding impulse as the change in momentum provides a clear framework for analyzing situations in both mechanics and dynamics, illustrating its critical role in the study of motion.