All Questions
9
questions
0
votes
2
answers
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Getting 2 different answers when finding spring constant $k$ when gravity is involved
OK, so I've been wracking my brain for the past hour trying to figure out how to calculate k in a problem like this:
A mass of 10 kg is attached to a spring hanging from the ceiling. It is released,...
0
votes
3
answers
499
views
How do I get the negative sign in the expression for Gravitational Potential Energy?
From universal law of gravitation, gravitational force exerted on a body of mass m by another body of mass M is
$$ \mathbf F = \frac{GMm}{x^2} $$
where x is the distance between the ...
-1
votes
2
answers
2k
views
Potential at Center of Earth
If using the surface of the earth as a reference point how much work is needed for gravity to pull me to the center. Is it negative infinity or am I wrong? Also is a single value of potential ...
- 53
4
votes
2
answers
7k
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Why is the gravitational potential inside a hollow sphere same as that of the gravitational potential on the surface of the hollow sphere? [duplicate]
Gravitational potential inside a hollow sphere is given by $$V(r)=\frac{-Gm}{R}$$ Why is it the same as the gravitational potential on the surface of the hollow sphere, which is given by $\frac{-Gm}{R}...
- 43
2
votes
1
answer
1k
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Gravitational binding energy and integrated potential energy not the same?
Before looking up the formula for the gravitational binding energy of a uniform sphere, I simply figured that the general formula for binding energy of an arbitrarily-shaped mass distribution would be ...
- 10.5k
1
vote
2
answers
307
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Deriving gravitational potential energy - why is $r_0 = \infty$?
I'm wondering about some assumptions I have to make in deriving the gravitational potential energy. This arises from the following exercise:
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Since the net force acting on the satellite is ...
- 3,200
1
vote
2
answers
2k
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Deriving gravitational potential energy using vectors
Here is my attempt at derivation:
First you must find a vector function for the gravitational force.
By the inverse square law, the magnitude of gravitational force between two bodies of mass $m$ ...
- 1,585
1
vote
2
answers
265
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A little confusion in the derivation of potential energy of a shell
This is a paragraph and a figure from The Feynman Lectures, He's trying to prove the Shell theorem for gravity:
If we rearrange $dm=2\pi y \mu ds$ we obtain $\dfrac{dm}{2\pi yds}=\mu$. In this ...
- 3,093
0
votes
3
answers
3k
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Is my derivation of the potential energy formula $m*g*h$ correct?
I've just wondered where the formula $E_{pot} = mgh$ you learn at school comes from so I've tried to work it out - is my reasoning correct?
The change in energy is given by
$$\Delta E=\int_{e}^{e+h}G\...
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