WEBVTT
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Now the little prince wants to
know how fast this little body
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is going around.
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And well, we can just do f
equals ma analysis again,
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but use a different option
here for the description
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of the circle of motion.
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So we are going
to get minus Gm m1
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over r squared equals
minus mv squared over r.
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And here one r cancels,
and this m cancels.
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And that goes to plus.
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If we solve this for v,
we get v equals Gm1 over r
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and the square root of that.
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And so now the little
prince knows how fast
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this object is going,
given the radius here
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that we've calculated over
there with Kepler's laws.