All Questions
Tagged with potential-energy energy
69
questions
5
votes
2
answers
6k
views
Bound states, scattering states and infinite potentials
I am doing my first semester of Quantum Mechanics and we're using Griffith's Introduction to Quantum Mechanics. As he is introducing the Dirac delta function potential he explains bound and scattering ...
- 125
5
votes
4
answers
2k
views
Has $E=mc^2$ been experimentally verified for macroscopic objects with potential energy?
In relation to this question: What is potential energy truly?, I'm wondering if $E=mc^2$ has been experimentally verified to hold true for macroscopic objects with increased potential energy? I'm ...
- 4,064
4
votes
3
answers
3k
views
Relative potential energy vs Absolute potential energy
I have seen in many textbooks and sources which say that we can't experimentally measure potential energy but we can measure differences in potential energy.
$$\Delta U_g=-W_g$$
Choosing zero ...
- 181
3
votes
3
answers
3k
views
Why Energy is greater than min value of Potential in Bound state?
Griffiths describes bound and scattering states as follows:
Bound state : $E<V(-\infty $) and $V(+\infty $)
Scattering state: $E>V(-\infty)$ or $V(+\infty)$
Why is that Energy for a ...
- 432
2
votes
1
answer
290
views
Physics definition of work and lifting
My calculus text (Swokowski, Olnikc, Pence, 6th edition) gives the
formula for work as $W = Fd$ and then goes on to explain that if the
force varies over the distance the formula becomes an integral. ...
- 211
2
votes
3
answers
9k
views
Work done by gravity on falling object does not seem to equal change in mechanical energy
So I have some confusion here, I am sure I knew this at some point. Let's say an object of 10 kg is dropped from a height of 10 m. When it reaches the ground, the work done on the object should be ...
- 533
0
votes
1
answer
607
views
Linking the work-energy principle with potential energy in the context of gravitational fields
I am trying to derive the equation for gravitational potential energy $E=-GMm/r$. On the Wikipedia page for energy:
https://en.wikipedia.org/wiki/Work_(physics)#Work-energy_principle it says that $W=-...
0
votes
2
answers
323
views
System of potential energy
Is potential energy calculated between a system? More specifically, if we say 'potential energy of a ball with respect to earth', does it mean that the Earth + the ball is a system?
- 23
7
votes
3
answers
1k
views
How is gravitational potential energy $mgh$?
I know the derivation that $W=Fd$, hence $F=mg$ and $d=h$ so energy gained by the body is $mgh$ considering the body on the ground to have $0$ gravitational potential energy.
But the definition of ...
- 1,168
4
votes
3
answers
2k
views
In physics sometimes we find energy that is negative. What does the negative sign indicate?
Sometimes we see energy that is negative, for example, the energy of an electron in orbit. We know energy is something that can do something. In this view does negative energy mean something opposite ...
- 279
4
votes
1
answer
218
views
Double counting potentials in $N$-Body Problem?
I suspect an error in my “Classical Dynamics” lecture notes but my lecturer doesn’t agree with me so I need your help!
We assume that in the $n$-body problem, the force between particle $i$ and $j$ ...
- 145
3
votes
1
answer
2k
views
Why is the potential energy of a particle in a travelling wave maximum at the mean position?
I mean, we calculate the speed of a wave (in a string) by considering the tensional force as a centripetal one (that's obviously an approximation), so shouldn't potential energy decrease in the ...
- 417
3
votes
1
answer
537
views
Doubt in the expression of Lagrangian of a system [duplicate]
There is a problem given in Goldstein's Classical Mechanics Chapter-1 as
20. A particle of mass $\,m\,$ moves in one dimension such that it has the Lagrangian
\begin{equation}
L\boldsymbol{=}\...
- 436
2
votes
4
answers
491
views
How can we have negative work in electrostatics, if $W=(\epsilon_0/2)\int\! E^2\ \mathrm{d}\tau$?
This question is motivated by Section 3.2.3 in Griffiths.
Therein, we are considering the force of attraction between a point charge and an infinite conducting plane. One can calculate the field ...
1
vote
2
answers
11k
views
Work done relation to potential energy
I know work done is negative of change in potential energy, I.e., $W=-(∆U)$.
It means that Work done against a force (or work done on a system) increases its potential energy.
And Work done by a ...
- 356