All Questions
15
questions
-2
votes
2
answers
159
views
Thought experiment: Where does potential energy come from if matter is created from energy?
Let's do a thought experiment:
Assume that I have a machine that can convert energy into matter with 100% efficiency i.e. it can create any amount of matter in a small space so long as I pay it's ...
- 121
-1
votes
3
answers
426
views
How does gravitational potential energy work in a very large distance?
Consider a thought experiment (that I made when I was in high school) involving a universe with only two objects: a massive planet and a small asteroid. Initially, they are millions of light-years ...
- 109
0
votes
1
answer
48
views
$N$-body simulation: total energy is conserved, but what about the energy of a specific particle? [closed]
It is clear that the total energy in a full gravitating $N$-body simulation should be conserved, but what about the energy of an individual particle? Is this not conserved, since the potential is ...
0
votes
2
answers
21
views
Constant energy in universe and spacecraft accelerating [duplicate]
Given that the energy in the universe is constant, how is it that spacecrafts traveling far distances sometimes get a boost by falling into the gravitational field of a planet? Acceleration caused by ...
- 107
1
vote
2
answers
190
views
A question on vertical spring mass systems
For a given mass attached to a vertical spring (near the surface of the earth), how do we know that the equilibrium point is halfway between its oscillation? (Let the height at the bottom of ...
- 155
0
votes
2
answers
88
views
How to derive the equation $-G\frac{Mm}{r_1}+G\frac{Mm}{r_2}=\frac{1}{2}mv_1^2-\frac{1}{2}mv^2_2$?
I was just wondering how the following equation is derived:$$-G\frac{Mm}{r_1}+G\frac{Mm}{r_2}=\frac{1}{2}mv_1^2-\frac{1}{2}mv^2_2~?$$
I already understand why the work $W$ done in moving an object ...
- 379
4
votes
2
answers
586
views
Feynman Lectures Chapter 4.2: Understanding the weight-lifting machine visually
Why a non-reversible weight lifting machine cannot lift higher that a reversible one is related to my current post, but everyone in that thread seems to have understood how Feynman's simple machine ...
- 216
0
votes
1
answer
152
views
What is the total energy of a object if i throw it so far from the earth that it doesnt move towards earth? It seems there is energy loss
Let us assume that i throw a object A with velocity V_A. Then it reaches certain height H_A. At that point it has total energy which is equal to its potential energy and it comes down converting PE to ...
-1
votes
2
answers
61
views
Constant gravitational acceleration $g$ and energy
I've been taught that $g$ is constant for different masses and that if I were to drop a heavy object and a light object from the same height then they would reach the ground at the same instant with ...
-1
votes
2
answers
796
views
Why is the work done by the parallel component of gravity equal to $mgh$?
I understand the mathematics behind why they are equal but I don't understand it in terms of intuition , for example when moving a cart along an incline plane the work done by the parallel component ...
- 207
3
votes
2
answers
1k
views
Gravitational Binding Energy
Lets define the Gravitational Binding Energy of a set of point masses as the work required to separate all point masses by an infinite amount.
First Question: Is the amount of energy required to do ...
1
vote
5
answers
7k
views
If a body is at rest at Earth's surface, can we say that its kinetic and potential energy are $0$ simultaneously?
If a body is at rest at Earth's surface, can we say that its kinetic energy $E_{\textrm{kin}}=0$, and its potential energy $E_{\textrm{pot}}=0$ also? Because its velocity $v$ and height above ground $...
user73555
1
vote
1
answer
142
views
Could an orbiting mass generate power?
If an heavy object (e.g. 10 tons) orbiting around Earth at 370 miles high, is connected with a cable back to Earth, we assumed either Earth is going to pull the mass or vice versa (or it will fall ...
- 113
4
votes
1
answer
515
views
Would the Moon drift away from the Earth due to extraction of tidal energy? [duplicate]
Possible Duplicate:
Why does the moon drift away from earth?
It seems to me that, due to conservation of energy, the moon would drift away from the Earth if humans began extracting large amounts ...
0
votes
2
answers
438
views
Calculating kinetic energy?
Would this be a valid equation to calculate kinetic energy created from a drop from a height:
$$E_{kinetic} ~=~ v_{vertical}tmg$$
Velocity multiplied by time gives distance. Distance multiplied by ...
user8791