All Questions
Tagged with energy potential-energy
480
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Violation of energy conservation due to Lorentz Force?
We know that work done by Lorentz Force $q(\vec{v}\times\vec{B})$ is $0$ on moving charge in magnetic field as velocity is always perpendicular to the force. This means that kinetic energy remains ...
- 1,168
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3
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189
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Where does an object get its energy from and what does it mean?
It is stated that an object in motion acquires "kinetic energy" while an object under the influence of gravity when raised to a height acquires "potential energy" but I have a ...
- 442
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6
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Does potential energy actually exist? Or is it just a useful mathematical model? [closed]
The title basically covers it. I've actually thought about this question for a while now, and I am still not sure if I have a definitive answer. Most potential energies seem to just be the work that ...
- 183
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Why Doesn't the Amount of Work Determine the Elastic Potential Energy in Springs and Gravitational Potential Energy? [closed]
Why isn't the amount of work done on the spring the determining factor for the amount of elastic potential energy stored in a spring?
I learned that the change in potential energy is a result of the ...
- 53
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2
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44
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Potential energy separately for each object
Potential energy change is :
$\Delta U = -W_{int}$ where $W_{int}$ is the internal forces.
For the ball which is falling down towards earth, we can write:
$\Delta U = -(W_{earth} + W_{ball}) = -(K_{...
- 137
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Elastic potential energy formula
From the Wikipedia page on elastic energy, we can find a bunch of formulas to describe it. For example, in the continuum section it talks about energy per unit of volume (density?):
$U=\dfrac{1}{2}C_{...
- 495
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106
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Change in potential and kinetic energy after a photon is absorbed by a electron
This is a question from the AP Physics 2 2022 FRQ. Why does the potential energy of the atom and the kinetic energy of the electron decrease after a photon is absorbed? Shouldn't both of them increase?...
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2
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143
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Potential energy density of a fluid in motion
If I have a fluid in motion at a given time and I know its pressure $p$ everywhere, I know its dynamic viscosity $\mu$ and I know its velocity field $\vec V$.
This system must hold some intrinsic ...
- 133
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Force in the Casimir effect
In the Casimir effect, after performing the regularization, it is found that the zero point energy between two conducting plates in a distance $L$ from eachother is (in the 1D case),
$$E=-\frac{\hbar ...
- 97
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2
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55
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Work done by gravity confusion
Say we had an object at height $h$ in a gravitational field, and of mass $m$, its GPE would equal $mgh$, now say we dropped it and it fell a distance of $h$, the work done on the object would be equal ...
- 195
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4
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204
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Circular reasoning involving conservation of energy and the definition of potential energy? [closed]
This might seem a dumb question but it is at the heart of mechanics.
We learn that in our universe the total energy of a closed physical system is conserved, never destroyed, never created, only ...
- 2,987
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88
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Equilibrium of a body with potential energy as a function of position
We know that if the potential energy of a body, say $U(x)$ of a body is known as a function of its x-coordinate, for equilibrium, $$\frac{dU(x)}{dx} = 0$$ Also, several sources suggest that for the ...
- 301
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91
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Where does the energy goes if the force is parallel to the displacement? [duplicate]
So, we all know that if force is perpendicular to the displacement, then work done is 0. But to generate force, I have to use up some of my energy. Had the angle not been perpendicular, my energy ...
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2
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286
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Shouldn't the electric potential energy decrease with separation regardless of whether the charges are positive or negative?
I was revising Electric Fields and it came up that if a positive charge moves in the direction of the electric field (so away from a positive charge), then the electric potential energy will decrease ...
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Energy in electric field calculated in two different ways
The equation for the energy density in a region of space where there is electric field, $\epsilon_0E^2/2$ implies that energy in the electric field can only be positive. Consider, however, the energy ...
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