# Tag Info

### Is gravitational binding energy or gravitational self-energy a source of gravity?

Is gravitational binding energy or gravitational self-energy a source of gravity? Yes. If gravitational theory satisfies the strong equivalence principle (SEP) then the gravitational binding energy ...

### Is gravitational binding energy or gravitational self-energy a source of gravity?

To work out the gravitational mass of a star you would have to include the rest mass of its components, their internal energy and their gravitational potential energy. The sum of the latter two terms ...
Accepted

The usual defination of force in terms of potential energy is $$\vec F=-\nabla U$$ ...However the minus sign over here seems just a convention Yes. It is a convention. But it is a long-established ...

Consider this example of some field potential energy profile : Field's potential energy gradient at particular point is a vector which points to zones with higher potential energy (by definition of ...
Accepted

### Some books write $V(\vec{r})$ instead of $V(r)$ as a notation for the electric potential, so which one is right?

In general, electric potential is a function of the vector position. Sometimes the vector notation is reduced to a scalar due to spherical symmetry.

### Energy gained by a black hole

John Duffield is talking about dropping an electron into a black hole. i.e. You start it from rest and the only energy it has is its rest mass energy when it is far from the black hole. In this case, ...
Accepted

### Electric potential difference due to gravity

The gravitation-induced electric field in and near a metal has been extensively studied by researchers trying to measure the gravitation force on positrons and antiprotons. In their original 1966 ...

### Electric potential difference due to gravity

As the electrons in the conductor are free, they will experience acceleration due to the force of gravity. This force, will cause the electrons to move downwards, this means that the new charge ...

### How to calculate magnetic force using differentiation of magnetic energy?

You get higher energy with increasing distance, because you assume constant currents in the loops. That is the correct result, because the farther apart the loops are, the less their fields cancel ...
1 vote
Accepted

### Expression for Potential energy of a hanging mass

Potential energy is never an absolute value - it is always measured relative to some base configuration or point that is assigned zero potential energy. And the location of this base point is ...
1 vote

### Expression for Potential energy of a hanging mass

Because you need to choose a reference frame. It's not mandatory to choose the origin at the level of the ground, it's possible to choose the origin wherever you want but you must be consistent with ...
1 vote

### Can work be 0 but the potential energy still increase?

Can work be 0 but the potential energy still increase? The net work on a charge can be zero while the potential energy of the system of charges increases. But since the integral of work from the ...
1 vote

### Gravitational potential energy of a galaxy

Your method is not correct. If I understood correctly, you obtained $U$ by integrating: $$U=Gm_R\int_0^R \frac{dm}{r}$$ with: $$dm=2\pi r\rho dr\\ m_R=\int_0^Rdm$$ and $R$ the hard cutoff of the ...
1 vote

### How can mechanical energy be preserved if the potential energy is negative?

Thus, the potential energy will be negative, but the kinetic energy cannot be negative. The potential energy will be negative relative to a point an infinite distance away from the Earth where the ...
1 vote

We want to uphold the convention that the potential energy is defined such that: $$U(r)= -\int_{\infty}^{r} \vec{F} \cdot \vec{dr}$$ This convention implies that; $$\vec{F} = -\nabla U$$ To see this, ...