What is escape velocity?

Layers of the Atmosphere
Image credit: Dreamstime.com

This term is very common in rocket science. Escape velocity is the minimum speed needed for an object to escape from the gravitational influence of a massive body. For example, you want to go out to play in the park, however, your mother doesn't let you out until you have completed your studies. You keep hovering around your door but you can not go out until you complete your work. In this case, doing your work lets you go out of the house's orbit thus making it your escape velocity.

Another example- when a spacecraft (going to Mars) is released into the exosphere, it is still in the Earth gravitational field. If the speed of the spacecraft is at least equal to the escape velocity of Earth, then the spacecraft will be flung out of the atmosphere.

This is the formula of escape velocity:





This is a general formula for calculating the escape velocity of any object trying to escape a planet,  a moon's gravitational force or any other massive body's pull. A gravitational constant is a small number that represents the amount of gravity acting on a certain area. The mass and radius are of the body, the object is trying to get away from.

DID YOU KNOW?

Luna 1
Image credit: Wikipedia

• Luna 1 (launched in 1959) was the first man-made object to escape Earth's gravity. 
• Jupiter has the greatest escape velocity amongst all planets. Escape velocity is directly dependent on the gravity of the planet. The most massive planet will have the maximum escape velocity. Obviously, in the case of our solar system, Jupiter wins. 
• The escape velocity in a black hole from the event horizon (the place around the black hole from where nothing can escape) is exactly the speed of light (approximately 2 99 792 kilometres per second)