TBR Physics ch2 #2

[annabelle17]

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Hey,

Question on Physics, Chapter 2 on "Forces, Circular Motion, and Gravitation". In Passage I, question 2, it says that r is tripled. However, because the potential energy is negative, increasing the denominator will "increase" the PE instead of decrease right?
It's the same for Question 5. The graph of potential energy is an increasing graph isn't it? The correct answer is D for question 5 and that graph is increasing right? The answer explanation says that it's decreasing... confused.

Thanks!
A

 

[DrknoSDN]

If your talking about Gravitational potential energy you should think of the equation as F= -GMm/r^2
at r=infinity the potential energy is said to be zero and as a general rule when things get closer the PE goes down. (becomes negative,,, thus the minus sign in front of the G)

So yes increasing R makes the potential energy less negative. Weird question to answer without looking at the problem but hope the concept helps.