What is escape velocity?

Escape velocity refers to the initial velocity required for an object to escape the gravitational pull of a celestial body, such as a planet or moon, without any additional propulsion. This concept is grounded in the principles of gravitational potential energy and kinetic energy. Specifically, for an object to leave a celestial body's gravitational influence, it must have sufficient speed to overcome the gravitational pull that acts on it.

When calculating escape velocity, we consider that an object must reach a speed where its kinetic energy equals or exceeds the gravitational potential energy acting on it. This occurs regardless of atmospheric conditions, making the atmospheric effects irrelevant in defining escape velocity itself.

The other options present concepts related to motion but do not accurately define escape velocity. For instance, while breaking through the atmosphere may involve achieving a certain speed, it does not accurately encapsulate the specific condition of escaping gravitational forces entirely. Similarly, the maximum speed of an object in free fall pertains more to the instantaneous speed due to gravity rather than the speed needed to leave that gravitational field. Lastly, average velocity in circular motion describes a different aspect of motion altogether, relating to the path taken around a circle, rather than the speed required to break free from gravitational attraction.