10
votes
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 ...
- 15k
7
votes
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 ...
- 126k
4
votes
Accepted
Minus sign in Force potential relation, a convention?
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 ...
- 15.7k
3
votes
Minus sign in Force potential relation, a convention?
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 ...
- 11.1k
3
votes
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.
- 56
2
votes
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, ...
- 126k
2
votes
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 ...
- 7,851
2
votes
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 ...
- 6,311
2
votes
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 ...
- 35.3k
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 ...
- 44.3k
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 ...
- 116
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 ...
- 67.5k
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 ...
- 8,651
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 ...
- 67.5k
1
vote
Minus sign in Force potential relation, a convention?
Various times that I have tutored physics (way in the past) I use a math analogy to convince someone that the force MUST be the negative of the gradient of the potential function. No conventions need ...
- 1,567
1
vote
Minus sign in Force potential relation, a convention?
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, ...
- 6,311
Only top scored, non community-wiki answers of a minimum length are eligible