Gravitation 2

What is escape velocity?

• If you throw an object straight up, it will rise until the the negative acceleration of gravity stops it, then returns it to Earth. Gravity's force diminishes as distance from the center of the Earth increases, however. So if you can throw the object with enough initial upward velocity, so that gravity's decreasing force can never quite slow it to a complete stop, it's decreasing velocity can always be just high enough to overcome gravity's pull. The initial velocity needed to achieve that condition is called escape velocity. Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor 

• Escape velocity is defined to be the minimum velocity an object must have in order to escape gravitational field of the Earth, that is, escape the Earth without ever falling back. The object must have greater energy than its gravitational binding energy to escape the Earth's gravitational field. So,

Kinetic energy (object) = Gravitational potential energy (Earth)

m = mass of the object

M = mass of the Earth

G = gravitational conctant

R = radius of the Earth

v = escape velocity

• The value evaluates to be approximately 11 000 m/ s. So, the object which has this velocity at the surface of the Earth, will totally escape the Earth's gravitational field. Answered by: Yasar Safkan, B.S. Phsyics Ph.D. Candidate, M.I.T.

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