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considering a Planet 1 and a Planet 2, where 1 is extremly heavier than 2 and 2 is going in Planet 1's orbit. Two questions

1) howto get the expression v = - G m2 m1 / r

2) if we consider the energy < 0, we can get to an expression as

v < sqrt (2GM2 / r)

howto get Vx and Vy for that V ?

(r is the radius.)

Hints and other help are welcome. Thanks.

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# Orbits and gravitacional field

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