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by lydigihome
Tags: gravitation
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Nov9-09, 02:33 AM
P: 6
X and Y are two planets. Each of them has a low-altitude satellite revolving in a circular orbit to the planet. If the two satellites are observed to have the same period,

"then X and Y must have nearly the same average density"

why is like that?


An object of mass m is released froma spacecraft at a distance 3R form the centre of the earth which has radius R and mass M. On reaching the earth's surface, the increase in kinetic energy of the object is:

how to work it out
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