# Gravity

This post is all about gravity. All the review made it clear that I needed to work on Gravity.

G-6.67*10^{-11} Nm^{2}/kg^{2}

F_{g}=-GMm/r^{2}

U_{g}=-GMm/r

(the negative means that gravitational potential is 0 at infinite distance)

both of those are given on table

g(or gravitational field)=GM/r^{2}

so acceleration of an object in orbit is GM_{e}(6*10^{24})/(6.3*10^{6}+r)^{2}

velocity of an object in UCM since F_{c}=F_{g}

mv^{2}/r=GMm/r^{2} v^{2}=GM/r v=(GM/r)^{1/2}

^{}

^{}Total energy of an object in orbit

E=KE+U_{g}=.5mv^{2}+ -GMm/r= .5mGM/r-GMm/r=- .5GMm/2r

Escape Velocity

.5mv^{2}=GMm/r v^{2}=2GM/r v=(2GM/r)^{1/2}

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