All Questions
18
questions
0
votes
2
answers
41
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Where did potential energy disappear in this case?
Just a new thought experiment. We know that the kinetic energy depends on frame of reference as do work and velocity. Now we can consider a falling ball. It converts potential energy to kinetic energy ...
- 11
0
votes
2
answers
488
views
Is most of the energy in the universe potential energy?
So I asked a question about what would happen in regards to gravitational potential if I left earth and then vaporized it. The answer I got was that the Mass would still remain the same and even if ...
0
votes
0
answers
77
views
If kinetic and potential energy are relative, how do they exert a gravitational force? [duplicate]
I am imagining two bodies flying through empty space near the speed of light relative to their (distant) surroundings. Let’s say they are a bowling ball and a tennis ball. They are not moving with ...
- 1
0
votes
3
answers
152
views
If a system is placed in a gravitational field, can you define internal energy for it?
My textbook says that internal energy for a system can only be defined if the system is isolated i.e. it has no external $K.E.$ and is not present in any external force field. But why? Why is it ...
- 837
1
vote
1
answer
93
views
Some questions regarding graviational potential energy and the concept of potential energy in general
Starting off, I first want to know the relation between work and potential energy.
$\Delta\mathbf U = - W $
How was this expression formulated?
Moving on,
My second doubt was in the derivation of the ...
- 82
0
votes
1
answer
109
views
Does a rolling ball take slower to reach the ground than a dropped non rotating ball from the same height?
I know in a ramp this isn’t true but there, the path is one dimensional.
However, here after the rolling ball goes off of the edge with a certain angular velocity, is the object's angular velocity ...
- 101
6
votes
2
answers
523
views
Can I use the expansion of the universe to create or destroy energy?
Imagine I have a setup like this:
(The objects are not attached to each other. The red objects are much heaver than the black one, and the setup is balanced.)
This setup has a non-zero ...
- 241
0
votes
2
answers
530
views
In the tunnel through the Earth thought experiment, how does total energy of a particle vary when it goes from surface of the Earth to its center?
In the typical tunnel through the center of the Earth thought experiment, a particle at the surface would oscillate between the two diametrically opposite points ignoring the rotation of the Earth. ...
- 3
1
vote
0
answers
25
views
Proportionality of distance to work in differing conditions
Why is Work done by $F_{grav}$ and EMF proportional to distance but work done by $F_{elastic}$ proportional to the square of the distance?
- 343
1
vote
1
answer
213
views
When an object is in free fall from rest at an infinite radius, is its potential energy proportional to its clock rate?
The total energy $E$ of an object in free fall from rest at an infinite radius is known to be
$$
E = m c^2
$$
As the object falls, its energy doesn't change since the object is merely moving freely ...
- 43
-1
votes
1
answer
35
views
Why can't momentum be used to compare something moving linearly and something falling
We're having a discussion in the office about the difference between using momentum and kinetic energy. Here is the example scenario.
Discussing an equivalent height for something to fall compared to ...
- 99
-1
votes
1
answer
509
views
Energy question involving gravity
So i'm doing this homework problem and its not working. This is it,
The radius of Saturn (from the center to just above the atmosphere) is 60300 km (60300✕103 m), and its mass is 570✕1024 kg. An ...
- 101
10
votes
3
answers
4k
views
Can an object falling in vacuum generate electricity by itself?
When an object falls through vacuum, gravitational potential energy is converted to kinetic energy. Is there some way to get electrical energy out of the equation by itself (i.e. somehow convert the ...
- 277
-1
votes
1
answer
1k
views
Calculating Potential Energy
I'm familiar with the potential energy equation, but I'm concerned with the value of 'g' in it. I know that, at sea level, earth's gravitational acceleration is 9.81 m/s/s. So I know that within the ...
- 307
1
vote
2
answers
3k
views
Does a mass falling towards the earth obey conservation of energy?
I'm trying to grasp basic concepts of energy and I have a question regarding conservation of energy.
According to Feynman's book and Wikipedia, the law of conservation of energy states that ...
- 394