# Engineering Physics

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At a location 4Re away from the center of the Earth, you release a 2kg object from rest. How fast is the object traveling when it is 2Re away from the center of the Earth?

Re = 6.4 x 10^6 m
Me = 6 * 10^24 m

• Engineering Physics -

PEi = - GMem/4Re
= KEf + PEf
= KEf + [- GMem/2Re]
So KEf = GMem/2Re - GMem/4Re
or (1/2)m v^2 = GMem/2Re
v^2 = G*Me/Re

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