Physics Concepts for JEE 2016: Escape Velocity

A body on a planet is under the influence of the planet’s gravity and is bounded to it. Even a satellite revolving around a planet is said to be in bounded motion because it’s moving under influence of the planet’s gravitational field.

Taking potential energy at infinity to be zero as a reference, when a body is bounded or under the influence of a planet’s gravity, its total energy will be negative. If we impart some kinetic energy to the body, its total energy increases, and if its total energy becomes zero or positive, we can say that it comes out of the influence of the gravitational field of the planet.

Thus the velocity imparted to a body at which its total energy becomes zero or more, at that velocity it will move away from the planet and escape from the gravitational field of the planet. This minimum velocity is called escape velocity for that planet which is measured relative to the planet’s surface. Watch the concept video on escape velocity given below –

When a satellite is revolving around a planet then certainly its velocity of motion (orbital speed) is less than the escape velocity. If by some external impulse or some other means its velocity is increased to escape velocity then the satellite will escape into space and will be free from planet’s gravitational interaction. Watch the concept video on escaping the satellite given below –

To understand the concepts in better way, see all the example videos given below on with more applications can be asked in different ways:

Example Video – 1:

Example Video – 2: