Practice portal › Gravitation › Escape Velocity
Asked in AIEEE 2002 · Escape energy
To just reach infinity the body needs enough kinetic energy to wipe out the gravitational potential energy at the surface.
That potential energy is U=-(GMm)/R, so the required K=(GMm)/R.
On the surface g=(GM)/(R²), so GM=gR².
Substituting gives K=(gR²m)/R=mgR.
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