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
19 views

Why is force negative if PE increases?

I'm looking at the PE vs force graphs for gravity, and it doesn't make sense to me. As potential energy increases (and the object goes higher above the ground), F=-mg. But if I'm raising an object up, ...
1
vote
3answers
53 views

how could Kinetic energy increase if no energy was there in the system?

i was reading Physics-Halliday, Resnick, Krane(fifth edition) there on page 638 it is written: if the external agent does positive work in assembling the charge ...
0
votes
0answers
15 views

Where is the zero electric potential energy point?

Does the point of the electric potential energy of zero is defined by human or dominated by the indefinite integral of the electric force?
5
votes
1answer
40 views

Understanding potential energy

I am self-studying the classical mechanics using the book by Taylor, and I have a question about the potential energy. The book (pg 111) says: If all forces on an object are conservative, we can ...
0
votes
1answer
21 views

Is it possible to determine how many electrons there are in a plate from its voltage?

We've just stared doing voltage in school, and so I wondered if this is possible :) If I charge an insulated metal plate using an EHT to something like 5kV, then I've added electrons to the plate. My ...
-2
votes
0answers
58 views

Electric potential inside a solid sphere [on hold]

We have charged solid sphere and have to find electric potential inside it. I tried it by two methods, By integrating $\int \vec{E}\cdot\text{d}\vec{r}$ for both outside and inside the sphere ( ...
0
votes
1answer
22 views

Working with the problems related to potential energy

Consider a spring mass system. A block is attached to a light vertical spring which is stretched under the load of block and this system is at a height $h$ from the ground. Now my problem is ...
0
votes
0answers
29 views

What is the relationship between potential energy and electrical potential?

I actually always thought this was trivial, now I am not so sure. For a potential $\phi$ the potential energy is $V=q\phi$ where q is a test charge. Now I am thinking this may work differently in two ...
0
votes
1answer
33 views

Understanding electric potential in the context of gravitational potential?

I'm trying to understand the concept of electric potential and the significance of an electric field being related to the gradient/derivative of an electric potential. I found this question that ...
-5
votes
0answers
32 views

Is 12-6 Lennard-Jones potential smooth confining potential? [closed]

It's obvious that 12-6 LJ is a 2-body potential. The potential $V$ is said to be a confining potential $V(\pmb{q}) \to \infty$ whenever $\pmb{q}_i \to \infty$ or $||\pmb{q}_i - \pmb{q}_j|| \to ...
-1
votes
0answers
35 views

Self enery of a sphere [closed]

If we have a sphere of radius 2R in which there is a cavity of radius R with concentric centre . Now we have to find self energy. I searched and got 3 methods : 1) U'' + U' + U* = U In this we ...
0
votes
2answers
65 views

Does contracted spring weigh more than stretched one?

(One of examples that potential energy contributes to mass.) Does hot object weigh more than cold one? (One of examples that kinetic energy contributes to mass.) If these are true and justified by ...
0
votes
1answer
44 views

What is the difference between the potential difference and potential energy of an electron?

What is the difference between the potential difference and potential energy of an electron? Let's take an example the potential difference (PD) across a resistor. if there's a current flowing, the ...
0
votes
2answers
66 views

Whats the meaning of this equation relating electric field and potential energy?

My electrodynamics teacher was explaining that it is required to apply some energy (or do some work) on charges in order to arrange them in space. When he stated an example about energy in a capacitor ...
0
votes
1answer
19 views

Does a charge difference necessitate a potential difference?

Consider two metal objects, X and Y that when connected by a conducting wire results in a transfer of electrons from Y to X. What can be concluded about X and Y before the connection was made: ...
0
votes
1answer
20 views

Problem involving Energy Method and Non-conservative Forces [closed]

I've got a problem in my physics I class that's got me stuck at the moment. A box is placed onto an angled plane so that it compresses a spring. When released, how far up the plane does the box go? ...
0
votes
2answers
27 views

Trouble understanding non-conservative force and work

I am having some trouble defining whether a force is conservative or not. In the example that we are working on a mass on a pulley system is used to cause a slender bar to rotate from rest to a ...
-1
votes
2answers
41 views

Potential Energy of Point Charges in a Square [closed]

So, an AP Prep book for the Physics 2 test has the following problem: My reasoning is as follows: The total potential energy = the sum of the PE of each of the 4 charges Which will equal 4x the PE ...
0
votes
0answers
16 views

What is the physical meaning of potential energy in a band diagram of a semiconductor?

According to this slide (from this website), the potential energy of an electron in a semiconductor is defined by the difference between the Energy level of the conduction band and the fermi level. ...
0
votes
2answers
51 views

What is the relationship between potential energy and inertia?

It seems to me that the two are very similar! Potential energy seems to either explain, or partially explain, directly or indirectly, the law of inertia. I already know that bodies do not move because ...
0
votes
1answer
56 views

Energy stored in electric field [duplicate]

I know that energy stored in electric field / unit volume = $\frac{1}{2} \epsilon\,E^2$. so can I say that for any configuration calculating $\int \frac{1}{2} \epsilon\, E^2 \,d^3r$ over whole space ...
0
votes
1answer
29 views

When a liquid solidifies why does internal energy fall? [closed]

Is it because the potential energy falls or is it because the kinetic energy falls .
1
vote
2answers
85 views

Relation between Electric field and potential

I am unable to understand from this - sign comes. Which step I have done wrong?
1
vote
1answer
35 views

Energy diagram of a planet with fixed mechanical energy

Consider the following energy diagram for the motion of a planet about a star. The centrifugal potential curve can be represented once I fixed the angular momentum $\vec{L}$ of the planet. To fix the ...
0
votes
1answer
31 views

Inconsistency in solving energy in free space given electric potential

So we have the equation $$ W= \frac{1}{2} \int_{volume} \rho_v V\,dv$$ and then after applying a vector identity which is $$\nabla \cdot (V\vec{D})=V(\nabla\cdot \vec{D})+\vec{D}\cdot (\nabla ...
1
vote
6answers
82 views

Why does positive work done by internal conservative forces $\implies$ decrease of potential energy?

Potential energy can be thought as the amount of work that the force can potentially do on the point because of its position. $$W=-\Delta U=U_{initial}-U_{final}$$ A positive work done by a force ...
3
votes
4answers
93 views

What is $V(x)$ in Schrödinger's equation?

In the time-independent Schrödinger equation it is stated that $$-\frac{\hbar^2}{2m}\frac{d^2\psi(x)}{dx^2}+V(x)\psi(x)=E\psi(x)$$ And it is common to give $V(x)$ some standard "forms": the infinite ...
0
votes
0answers
32 views

When should gravitational potential energy be included in the law of conservation of energy

I have a problem that says: A block of mass 0.249 kg is placed on top of a light, vertical spring of force constant 4 975 N/m and pushed downward so that the spring is compressed by 0.090 m. ...
1
vote
2answers
57 views

How does conservation of energy work?

I understand that the law of conservation of energy states that energy cannot be created or destroyed, it can only change from one form to another. This means that the total energy before a certain ...
0
votes
3answers
78 views

Zero Potential Energy Change in Raising a Mass

Suppose I am able to lift a body of mass $m$ up using a constant force $F=mg$ so that net acceleration is zero on it. I want to find the potential energy and the total energy of the body when I have ...
0
votes
0answers
11 views

Potential energy of a shell & point system

Consider the system of a point particle with charge $q$ and a spherical shell with uniform charge $Q$ and radius $R$ whose center is a distance $r > R$ away from the point particle. I'm trying to ...
0
votes
2answers
40 views

Relationship between work and energy in an electrostatic system

I am having problems understanding the relationship between the concepts of Work and Energy in a electrostatic system. As I know, the definition of Potential Energy is the ability to do work. In a ...
1
vote
0answers
33 views

Meaning of centrifugal term in the mechanical energy of a orbiting planet [duplicate]

For a planet under the effect of gravitational force the mechanical energy can be written as $$E=\frac{1}{2}\mu {\dot{r}}^2+\frac{L^2}{2\mu r^2}-\gamma \frac{m M}{r^2} \tag{1}$$ Where $\mu$ is the ...
2
votes
1answer
99 views

Why can't I use conservation of energy to find ratio of final velocities on different planets?

The question is An object of mass $m$ is allowed to slide down a frictionless ramp of angle $\theta$, and its speed at the bottom is recorded as v. If this same process was followed on a planet ...
11
votes
7answers
1k views

Why doesn't an object, despite having a non-zero potential energy stored in it, fall by itself from the elevation?

When an object is at a certain height, it has some energy stored in it as we have done some work on it to get it to that height. So when it already has energy, then why doesn't it fall off from the ...
1
vote
3answers
41 views

Interaction between magnetic moments and magnetic field

Consider a particle with a magnetic moment $\vec{m}$. For simplicity, suppose that this particle is a circle in the plane $xy$ which can rotate around its center of mass along the $z$ axis. If this ...
0
votes
2answers
14 views

Electric potential energy of a charge

Potential energy is the work done by the particle against a conservative force. Isn't it? when a charge is fixed on a free space and then when we bring another charge from infinity to a distance r ...
0
votes
1answer
30 views

Total potential energy in electric field?

if there are 2 charges generally potential energy of the system should be the sum of individual potential energy. but why the potential energy is half of the sum of every individual charge's potential ...
1
vote
1answer
49 views

Why do a conservative force try to reduce potential energy?

Mathematically I understood the reason why, for a conservative force, $\vec{F}=-\vec{\nabla}U$. Physically this means that a conservative force is always oriented in the direction of greatest ...
0
votes
0answers
58 views

Why is the longitudinal term removed to form the Lorentz force equation?

Beginning with the expression for interaction energy, and deriving the potentials form for the force on a test charge moving at velocity $\vec v$ yields: $$\vec F = q(-\nabla\phi - {D\vec A \over ...
0
votes
1answer
29 views

Directional derivative of the potential energy in the direction of the displacement in three dimensions

For a conservative force $\vec{F}=-\vec{\nabla } U \implies \mathrm dW= -\vec{\nabla} U \cdot \mathrm d\vec{s} $ Where $\mathrm d\vec{s}$ is the infinitesimal displacement. For a differentiable ...
1
vote
2answers
87 views

Physical meanings of kinetic energy

While studying energy on Sears & Zemansky's University Physics, I came up with a doubt on the meaning of kinetic energy. The book gives two possible physical interpretations of this quantity. ...
0
votes
1answer
17 views

About Electric potential

when we bring a unit positive charge from infinity to a point in the electric field EF does work on the charge and external work is also done on the charge in same amount but in opposite sign. then ...
1
vote
1answer
39 views

Mechanical energy $E<0 \implies $ the system is in a bound state?

In a gravitational field if a body has negative mechanical energy, then the system body-planet (or star) is in a gravitationally bound state. The explanation that I have in mind for that is: since ...
3
votes
0answers
58 views

Binding energy of a galaxy?

I'm a novice in physics and new to the forms, so please forgive me if this is a dumb question or if this is in the wrong section to be posted, but how would one find the gravitational binding energy ...
1
vote
0answers
39 views

Interpretation of a case of the double square well

Consider a 'double square well' potential (where $E < 0$) defined as: $$V(x) :=\begin{cases} -V_0~~~~~~~~~~~~~\text{for }\frac{b}{2} < x < \frac{b}{2} + a \text{ and } -a - \frac{b}{2} < ...
0
votes
3answers
30 views

Potential energy (in lifting an object)

When a man of mass 60 kg lifts a mass of 20 kg upto height of 20m. The energy spent by him will be $mgh$. My question is should we add the masses of both the man and the object?. (Competetive ...
0
votes
2answers
58 views

Confusion about Conservation of Mechanical Energy

I'm having a bit of difficulty understanding how to apply the idea of conservation of mechanical energy to a problem. One of the questions on my homework reads: A physics student shoves a 0.50-kg ...
1
vote
2answers
107 views

Difference between potential centrifugal energy and rotational/kinetic energy

I'm having troubles to understand the difference between kinetic energy and potential centrifugal energy in some situations. I make an example where I am confused. A object moves on a rod attached ...
1
vote
0answers
48 views

An interesting problem on potentials [closed]

I am thinking of an interesting problem on potentials. Consider a potential field $U(\mathbf R)$. Furthermore, consider a rocket with exhaust speed from 0 to $v$. I am wondering whether there is a way ...