Potential energy is the energy of a body or a system due to the position of the body or the arrangement of the particles of the system.

learn more… | top users | synonyms

0
votes
1answer
82 views

How do I found the Kinetic Energy of a mass being lifted?

I did an experiment where I lifted a mass and measured the force. I know the change in height, the mass, and the work of the pull. How can I use the work-kinetic energy theorem to find the final and ...
1
vote
0answers
73 views

Potential Energy of two masses

If two particles with masses $m_1$ and $m_2$ interact and are located at $\vec{s_1}$ and $\vec{s_2}$ have their potential energy $U$ defined by the modulus of their position vectors, how would I ...
1
vote
1answer
53 views

Gravitational PE lost v Elastic PE gained in mass - spring

If a spring has a load $m$ added to it (and so is extended by $x$), the gravitational potential energy lost by the mass will be $mgx$. The elastic potential energy gained by the spring is ...
3
votes
2answers
76 views

Multiple Definition For Gravitational Potential Energy?

This may just be a simple Misconception Question, here goes: Definition for Gravitational Potential Energy: The work done by gravity to pull an object to the ground. ...
2
votes
3answers
123 views

What has the potential energy: the spring or the body on the spring?

Particles have gravitational potential energy due to its position in the gravitational field. We say the particle has potential energy and not the Earth (the body doing the work). Why is it not the ...
2
votes
2answers
836 views

Work done by a non-conservative force and change in potential energy

I know that the work done by a non-conservative force is equal to the change in total mechanical energy (from Work-Energy Theorem). But I read in a place that "Non-conservative forces don't affect ...
0
votes
1answer
101 views

A question on Rolly polly dolls

I was reading on rolly-polly dolls when the following questions crept into my mind How exactly does center of gravity play a role which helps rolly-polly doll to stand up on its own? Can a ...
0
votes
1answer
94 views

What is meant by saying the work done by a conservative force is -(change in PE)?

I read through all related questions, and they are almost the same, but I still didn't understand this and so am asking again. What is meant when we say that the work done by conservative force is = ...
1
vote
1answer
162 views

Why isn't energy stored in a capacitor equal to just $QV$ when it is fully charged? [duplicate]

I just learned that the energy stored in a capacitor is electrostatic potential energy. Also potential energy is a state function and is independent of the path. So, when the capacitor is fully ...
0
votes
0answers
34 views

Strain energy density (potential energy of elastic continua)

This question has to do with writing down the potential energy of an elastic body, which obeys a generalized Hooke's law [; \sigma_{ik} = \sum_{klm} \lambda_{iklm} u_{lm} ;] Where $\sigma$ is the ...
1
vote
2answers
148 views

The “potential energy” degree of freedom?

I'm reading Schroeder's "An Introduction to Thermal Physics" and he mentions the vibrational degrees of freedom of a diatomic molecule: A diatomic molecule can also vibrate, as if the two atoms ...
1
vote
2answers
146 views

Is potential energy frame dependent in special relativity?

In newtonian mechanics, As far as I'm aware, only kinetic energy is dependent on frames of reference, since kinetic energy is a function of velocity(squared) and velocity is dependent on frames of ...
0
votes
2answers
171 views

Where does the energy go when you stretch a rubber band?

There is resistance when you stretch a rubber band. That makes sense to me because the energy you exert is turned into potential energy of the rubber band, but if you hold the rubber band in the same ...
3
votes
2answers
855 views

How far up an object is its gravitational potential energy taken from? [closed]

This is quite a brief question but, Is the $h$ value in $mgh$ taken from an object's base, middle of top. For example, if a person was $1.5m$ in height and they were standing on a hill of height ...
1
vote
3answers
79 views

Is there an example of a situation where you need a continuous spectrum?

If you had a hydrogen atom you could say that you want to be able to ionize them. But if you then add the potential due to the earth, e.g. ...
1
vote
1answer
101 views

Rolling down an arbitrary hill with friction

I had in mind this physical situation of a point mass rolling down a hill of some arbitrary shape ($y=y(x)$, for instance a parabola about $x=0$), with a peculiar friction force whose "expended work" ...
0
votes
0answers
193 views

Work done by flow of a fluid

I'm looking at the power a flow of steam in a turbine. I originally assumed that the kinetic energy of a moving section of steam was equal to (let $V$ be volume, $\rho$ be density, and $v$ be velocity ...
2
votes
0answers
80 views

Question about defining potential energy of a magnetic dipole placed in a magnetic field

We know that magnetic field is a non-conservative field, since it exists in closed loops. Then how can we define the potential energy of a magnetic dipole placed in a magnetic field ?
2
votes
1answer
79 views

What is minimum total energy?

I thought that the energy for a system is constant. But in a question in my physics book we have been asked to determine the minimum total energy from a graph of potential energy vs position? What ...
0
votes
1answer
113 views

Can't a hydrogen electron have net positive energy?

This page http://www.physicspages.com/2011/06/07/hydrogen-atom-series-solution/ is the 2nd half of a solution to the hydrogen atom Schrödinger equation. They derive that $E = -1/n^2 *$ (bunch of ...
0
votes
1answer
65 views

On the connection between forces and the principle of stationary action

Feynman tries to account for the relation between the principle of stationary action, which is a statement about the whole path of a particle, and Newton's second law, which is a statement about the ...
0
votes
1answer
93 views

Slingshot Energy into traveled distance [closed]

If I have a slingshot and I am told that when pulled it has about $E$ joules of energy, how do I compute the height at which an object of mass $m$ would travel if the slingshot is released in the ...
0
votes
1answer
36 views

Of the two variables (Q and V) in the equation of capacitor energy, which is better to take the average of?

$U_c = \frac{1}{2}QV$ I understand from the graph which it should be one half but not quarter, or taking the average of both. But it doesn't really matter to me which variable is on y or x axis? ...
0
votes
3answers
103 views

What is the definition of potential energy? [duplicate]

I have problems with this equation: $$U_G ~=~ G\frac{m_1m_2}{r}.$$ It's for potential energy of say something placed on Earth. But it intrigues me. $r$ is the distance from the very center of the ...
0
votes
1answer
103 views

Why is the equation for electric potential energy so counter-intuitive?

The equation: $U_E = Vq$ or $(Eq)d$. This works the same way as the equation for gravitational potential energy: $mgh$ But to me, for charges of different signs, the potential energy also varies. ...
1
vote
0answers
40 views

Approximate Electric Potential $V$ so that it is of the form $V(r) + V(\phi) + V(z)$

I'm trying to simulate the conductivity of a nanowire that is modeled by a cylindrical shell of infinite potential with benzene rings in the core of the wire. (This is based on a coiled-coil protein ...
0
votes
1answer
28 views

Can the electric potential corresponding to the negative plate ever be equal to anything bigger than zero?

I am doing my homework. I read my textbook. It says that the negatively charged plate is the low potential plate. It also shows a example of lower plate equal to 0V, I guess for simplicity. But what ...
0
votes
2answers
144 views

A little confusion in the derivation of potential energy of a shell

This is a paragraph and a figure from The Feynman Lectures, He's trying to prove the Shell theorem for gravity: If we rearrange $dm=2\pi y \mu ds$ we obtain $\dfrac{dm}{2\pi yds}=\mu$. In this ...
1
vote
3answers
164 views

How does The work done in going around any path in a gravitational field is zero implies conservation of energy?

In The Feynman Lectures, Feynman states: The work done in going around any path in a gravitational field is zero. This is a very remarkable result. It tells us something we did not previously ...
-4
votes
1answer
128 views

If systems minimize their potential energy, why do people climb mountains?

A person climbs a mountain. They convert the stored chemical energy of food in their body and back pack into heat energy on the mountain, and gravitational potential energy as they move towards the ...
4
votes
4answers
693 views

A confusion regarding an example in The Feynman Lectures

In The Feynman Lectures, In the chapter entitled Work and potential energy, Feynman states: The work done in going around any path in a gravitational field is zero. This is a very remarkable ...
0
votes
1answer
34 views

does $Q_AV_{AB}=Q_BV_{BA}$ in this case

Sorry fo unclear title but I can't find any suitable on for this question. Here is what my text book says about how to find out the energy of a system of charge of n particle. What I don't know is ...
1
vote
1answer
1k views

What is an effective potential in classical mechanics?

What is an effective potential in classical mechanics? I have read the wikipedia article and David Tong's lectures notes, but I didn't understand how an effective potential simplifies a situation or ...
1
vote
4answers
630 views

Why is $F=-\nabla V$?

I came across this equation $$F=-\nabla V$$ where $V$ is potential energy. I do understand that $$F(r)=-\frac{dV}{dr}.$$ Hence does this mean the nabla operator in this case means derivative? Because ...
1
vote
1answer
83 views

Derive frequency given potential using Newton's laws

A mass with mass $m$ has a potential energy function $U(x)$ and I'm wondering how you would find the frequency of small oscillations about equilibrium points using Newton's laws. I started by finding ...
0
votes
1answer
163 views

Deriving gravitational potential energy using vectors

Here is my attempt at derivation: First you must find a vector function for the gravitational force. By the inverse square law, the magnitude of gravitational force between two bodies of mass $m$ ...
0
votes
2answers
69 views

What is the meaning of this definition of potential energy?

The isolated system of particles is being observed. In the coursebook, $\vec F_\mu$ is by definition the vector sum of forces of all other particles acting on $\mu$-th particle. Usually, potential ...
0
votes
1answer
90 views

Hooke's Law Problem [closed]

This question assumes that the spring obeys Hooke's law. Say we have a spring Length $L$. The energy of said spring when extended will be $E=(kx^2)/2$. The extension $x_1$ of said string would be ...
0
votes
2answers
109 views

What is the binding energy in General Relativity?

In general relativity, the potential energy is given by $$V(r)=\frac{h^{2}}{2r^{2}}\left(1-\frac{2M}{r}\right)-\frac{M}{r}.$$ Solving $V^{\prime}(r)=0$, there are two points where circular orbits ...
3
votes
1answer
481 views

Feynman Lectures: Why a non-reversible weight lifting machine cannot lift higher that a reversible one?

Consider weight-lifting machines—machines which have the property that they lift one weight by lowering another. Let us also make a hypothesis: that there is no such thing as perpetual motion ...
0
votes
2answers
138 views

Definition for potential energy

I came across this definition for potential energy: If we let $T$ be the Kinetic energy, we have that: $$T = \frac{1}{2}mv^2 \implies T = \frac{1}{2}m{x'}^2$$ $$T'= mx'x'' = F(x)x' \implies \\T = ...
0
votes
1answer
100 views

Differential form of the law of gravitation potential

I have problem understanding transaction (operations and methods applied) for one equation to other equation. It is about gravitational potential. $${\vec F_{grav}=\frac{GMm_{obj}\vec R}{R^3}}$$ If we ...
4
votes
2answers
186 views

Is the Einstein Energy-Momentum equation $E^2 = p^2c^2 + m_0^2c^4$ valid only for Free Particles?

Is the energy -momentum relation $$E^2 = p^2c^2 + m_0^2c^4$$ satisfied only by free particles or even bound particles? Does the Energy refer to total Energy(including potential) or only (kinetic ...
0
votes
1answer
30 views

Electrostatic potential due to two charge system

When we calculate electric potential energy of a two particle system, say first I bring $+q_1$ and then I bring $+q_2$ against $q_1$'s electric field. Say I get that $q_2$ charge to a point $r$ ...
5
votes
3answers
1k views

Why is a conservative force defined as the negative gradient of a potential?

I'm learning about work in my dynamics class right now. We have defined the work on a particle due to the force field from point A to point B as the curve Integral over the force field from point A to ...
1
vote
1answer
133 views

Resistance and potential difference across it

I have this question that has baffled me for hours now. My question is what really happens when charge passes from one point to another in a circuit for eg what happens when it passes over a ...
0
votes
0answers
71 views

Sign of an electric field in electric potential energy problem

I was wondering why the electric field E in this problem is negative. Is it because the earth is negative? We can assume that near the Earth’s surface, a uniform electric field is set up thanks to ...
0
votes
2answers
330 views

Turning points of particle

A particle of mass $m$ and energy $E<0$ moves in a one-dimensional Morse potential: $$V(x)=V_0(e^{-2ax}-2e^{-ax}),\qquad V_0,a>0,\qquad E>-V_0.$$ Determine the ...
1
vote
3answers
61 views

Why is intermolecular potential energy given in 'per mole'?

I was just wondering that if intermolecular potential is the interaction potential energy of two atoms/molecules, then why do we give its value in J/mole? I don't understand why 'per mole' ...
1
vote
2answers
65 views

Proof that oscillations in 1d potential well occur between certain points

In >>this<< situation, a particle with energy $E$ will oscillate between the positions $x_1$ and $x_2$ indicated on the diagram. This simple fact is taught in many introductory courses however I ...