Question

What is escape velocity? And derive an expression for it?

Answer 1

In physics, escape velocity is the minimum speed needed for a free object to escape from the gravitational influence of a massive body. It is slower the further away from the body an object is, and slower for less massive bodies. The escape velocity from Earth is about 11.186 km/s at the surface.

To calculate escape velocity, multiply 2 times G times M, then divide that by r, and take the square root of the result. In this equation, G is Newton's gravitational constant, M is the mass of the planet you're escaping from in kilograms, and r is the radius of the planet in meters