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jwu
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Homework Statement
All we know the gravitational potential energy is U=-GMm/r. But when I got confused when I was trying to understand the proof of this equation.
Homework Equations
Here's what they did:
W by grativity=GMm(1/r2-1/r1)
Therefore, since △Ugrav=-W by grav, we get
U2-U1=-GMm(1/r2-1/r1)
Let's choose out U=0 reference at infinity.that is , we decide to allow U2→0 as r2→infinity. Then this equation becomes U=-GMm/r
The Attempt at a Solution
Here's my question:
What does it mean by "Let's choose out U=0 reference at infinity.that is , we decide to allow U2→0 as r2→infinity. Then this equation becomes U=-GMm/r"?
Why the U2 would approach to 0 when r2 approached to infinity? And what ti U=0 reference?
Thank you!