All Questions
9
questions
-2
votes
1
answer
75
views
Potential energy with different heights [duplicate]
If system consists of earth and ball and ball is dropped from height $h_i$ to $h_f$, then:
$\Delta U = -(W_{earth} + W_{ball})$ ($W_{ball}$ can be neglected since it's small)
$\Delta U = -(-mg(h_f - ...
- 1
2
votes
2
answers
356
views
Is $F=mg$ derived from Newton's law of universal gravitation $F=Gm_1m_2/r^2$?
If so, that means gravity is only 9.8 m/s^2 at the surface of the earth?
- 21
0
votes
2
answers
51
views
How does formula for universal gravitation between mass $M$ and mass $m$ collapse to $mg$ on Earth? [duplicate]
Can anyone give a mathematical demonstration of this? I assume it has to do with the fact that Earth’s mass is much bigger than the mass of any object on Earth, but I think it would be interesting to ...
- 556
0
votes
0
answers
31
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What's the difference between Potential energy ($mgh$) and gravitational potential energy ($-\frac{GMm}{r}$)? [duplicate]
Yeah one is for measuring potential energy between the objects of two masses $M$ and $m$
We recently started studying about gravitation and I'm really confused when swtiching back and forth, or can we ...
1
vote
3
answers
963
views
Why can gravitational potential energy be expressed both as $mgh$ and $-GMm/r$? [duplicate]
In these two different equations for the same (?) thing, not only is one directly proportional to height and one is inversely proportional to height, but they contain completely different variables, ...
0
votes
2
answers
2k
views
Range of Earth's gravitational field
We know that the acceleration due to gravity acting on a body situated h meter away from the surface of the earth is given by,
$$g' = (1 - 2h/r)g,$$ where $\,r$ = Radius of the earth ($R$) + $h$. Now ...
- 1,018
3
votes
1
answer
315
views
Is it mathematically accurate to simply objects to point masses when calculating gravitational forces between them? or is it just an approximation?
I tried searching for the exact mathematical proof that validates this assumption, but I couldn't find any.
Also, is this assumption still accurate if the density of the object resembles a planet (...
- 33
0
votes
0
answers
32
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Gravitational potential energy on the Earth's surface [duplicate]
We assume that gravitational potential energy at a height $h$ from the Earth's surface is $mgh$. Is that accurate or only approximately correct ?
Here is my approach.
On the surface of the Earth,
$...
user174490
2
votes
3
answers
2k
views
Two bodies of finite size treated as two point masses in Newtonian gravity
When discussing gravitation between two bodies of finite size, for instance Earth around the Sun, we suppose the mass of Earth and the Sun to be perfectly localized at the center of each body. Is this ...
user60924