All Questions
Tagged with homework-and-exercises potential-energy
395
questions
77
votes
8
answers
27k
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Does a thrown ball have kinetic energy at the top of the curve?
I'm going through physics with my 5th grade child. There is a question and answer that indicates that a airborne ball at the top of the trajectory does not have kinetic energy.
The diagram below ...
- 977
58
votes
15
answers
13k
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When a balloon pops and lets a brick fall, where does the energy come from?
Let's say a scientist attaches a 1 kg brick to a large helium inflated balloon, lets the balloon go, and then it reaches an altitude of 10 000 meters before it pops, dropping the brick.
The brick ...
- 1,298
13
votes
5
answers
4k
views
Why does the incline angle not affect how high a launched object will slide up a frictionless ramp?
I am seeing a problem with the solution given in this book. How did the height of the box have nothing to do with the incline of the ramp? Intuitively it would seem the higher the incline the higher ...
8
votes
3
answers
572
views
Potential energy of springs and gravity, and work of a force
I am currently really stuck on this problem and I am not sure how to actually solve it, I think I can reason it out logically but I do not know how to show it. Here it is and under I will show what I ...
- 81
6
votes
2
answers
2k
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Bertrand's theorem and nearly-circular motion in a Yukawa potential
The question has arisen as a result of working on part b of problem 3.19 in Goldstein's Classical Mechanics book.
A particle moves in a force field described by the Yukawa potential $$ V(r) = -\frac{...
- 1,031
6
votes
2
answers
2k
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Finding the components of the tensor for potential and kinetic energy
I have a rather poor understanding of what a tensor is, but enough to apply it to the biggest part of the classical mechanics I'm studying.
However, I've run into a small problem while studying "Free ...
- 1,373
5
votes
3
answers
2k
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If a car is *accelerating* uphill, does it *gain* kinetic energy?
I had an exam yesterday on physics (9th Grade), there was a question that confused me a lot. It said: "If a Gas Car is accelerating uphill, what happens to its G.P.E and K.E?"
A: It loses ...
- 61
5
votes
1
answer
1k
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How to show period is defined by $T=dS/dE$ (V.I. Arnold Mathemtical Physics) [closed]
I'm looking at a book by VI Arnold on mathematical physics and I've hit a roadblock pretty early on. I'll quote the question:
"Let $S(E)$ be the area enclosed by the closed phase curve ...
- 130
5
votes
3
answers
7k
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Electric Potential Energy of a charged conductor
My physics textbook asks (I translate):
A sphere of copper with a radius of 0.72 metres is charged with a Potential of 270,000 Volt. Find its charge and the electric energy it holds.
I found the ...
- 559
5
votes
3
answers
4k
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What was the amount of energy released in the 9/11 terrorist attacks?
I read somewhere on the internet that the amount of energy released by the terrorist attacks on the twin towers on 9/11 should have been of the order of 100 tons of TNT. This number surprised me, ...
- 9,910
5
votes
2
answers
4k
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Shape of a string/chain/cable/rope/wire? [closed]
The height of a string in a gravitational field in 2-dimensions is bounded by $h(x_0)=h(x_l)=0$ (nails in the wall) and also $\int_0^l ds= l$. ($h(0)=h(l)=0$, if you take $h$ as a function of arc ...
- 1,550
5
votes
1
answer
114
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Insecurity about introductory classical mechanics [closed]
This is a problem I encountered, but not a homework assignment, I'm not only just looking for solutions here... This is my first time encountering questions like this, I'm sure you remember the first ...
- 287
4
votes
3
answers
250
views
Why is my answer for height negative?
Question is simple. A ball is thrown upwards with initial velocity $v_0$. How high does it go up?
Assume down is negative and up is positive and no air resistance.
KE at bottom = PE at the top:
$\...
- 109
4
votes
1
answer
6k
views
Derivation of Interaction energy of Dipole - Induced Dipole Interaction
I see that the formula giving the potential (interaction) energy of a dipole and an induced dipole is $$V=-\frac{C}{r^6}$$ where $$C=\frac{\mu_1^2 \alpha'_2}{4 \pi \epsilon_0}$$ and that the formula ...
- 345
4
votes
2
answers
3k
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Proof of total energy is constant in a central force field
I saw many proofs of total energy is constant in a central force field. But all the proofs end up showing this formula $$m[{\dot r}^2 + r ^2{\dot \theta}^2 ]+ \int f(r)dr = E$$ is constant. But ...
- 1,149