All Questions
380
questions
0
votes
2
answers
27
views
Problem when deriving formula of the momentum of photons in photoelectric emission
Now I know this might be a small error on my part or some wrong assumption taken, but for some reason when I tried deriving the momentum, I ended up with a different value.
The momentum is given as:
$$...
- 3
1
vote
2
answers
75
views
How to understand $W=pc$ in Feynman's Lectures on physics?
Pictures below are from 34-3 of Feynman's Lectures on physics. I can't understand the red line.
The $p$ is momentum, $c$ is light speed. I can't understand the red line. I feel the author think $pc$ ...
- 351
0
votes
1
answer
43
views
Conservation of Momentum in particle splitting. Is it always conserved?
Let an intially stationary particle $A$ of mass $m$, if $A$ explodes such that it breaks into 2 equal pieces.(Assume no heat or sound energy loss)
The red point is supposed be the point at which the ...
- 367
1
vote
2
answers
83
views
Total Energy to Total Momentum
Suppose I have two particles with different masses and velocities. The momentums are as follows:
$$\mathbf{p}_1 = m_1 \mathbf{v_1} $$
$$\mathbf{p}_2 = m_2 \mathbf{v_2}$$
The total momentum is:
$$\...
- 2,599
1
vote
2
answers
262
views
What is the physical significance of momentum and energy in kinematics?
Thank you all for the insightful comments on my previous question Are the concepts of motion such as mass, momentum, impulse, work, energy, force etc. fictitious/abstract concepts or are they real &...
- 55
0
votes
1
answer
33
views
Confusion about Momentum and Energy and their conservation
I've heard that momentum is always transferred macroscopically while kinetic energy of an object can be transferred microscopically, as far as I know
Why? And how does it make sense, how do we know ...
- 29
0
votes
0
answers
55
views
Degrees of freedom in stress-energy tensor
The stress-energy tensor has 16 components, but this question is only about the 9 components $T^{ij}$ with $i,j=1,2,3$. According to Wikipedia, these components are defined as follows:
The components ...
- 1,440
8
votes
4
answers
1k
views
Why "time part" represents energy in Four-momentum?
I was going through Spacetime Physics by Taylor and Wheeler and came to a point where they said, and I quote,
In what follows we find that momenergy is indeed a four-dimensional
arrow in spacetime, ...
- 121
0
votes
0
answers
29
views
Can all kinetic energy from a punch be converted into the internal energy? What about momentum conservation?
I've found a solution for how fast you have to slap a chicken to cook it.
For example:
½m1v1² = cm2Δt
m1 = hand's mass (5 kg)
m2 = chicken's mass (2 kg)
c = 4185 J/kgK
Δt = 50 K
v1 = ± 409 m/s
...
- 11
0
votes
4
answers
64
views
Percentage change in K.E for a given change in momentum
I couldn't get through this 'easy question' that was in my morning exam, it goes
Q. If linear momentum of body is increased by 50%, then K.E of that body increases by....%
**My solution **
K.E = $E=\...
- 367
0
votes
4
answers
136
views
Kinetic energy and momentum [duplicate]
I was studying the conservation of momentum and energy and a question came to my mind. Both energy and linear and angular momentum are "numbers" that represent the symmetries in the ...
- 67
2
votes
3
answers
206
views
Energy and momentum & the relation between them
I am trying to wrap my head around energy, mass and momentum, especially in the more general scope of special relativity where massless objects moving at the speed of light also have momentum. So I am ...
- 219
2
votes
1
answer
138
views
How to convert from momentum to energy distribution? (relativistic electrons)
I am using a gyro-kinetic simulation tool 2103.16457 which solves the 3D Fokker-Planck equation for the electron population in tokamak plasmas and evolves plasma parameters self-consistently. In many ...
1
vote
1
answer
68
views
Conservation of Kinetic energy in splitting
If a stationary mass $M$ explodes into 2 masses $m_1$ and $m_2$ with velocity $v_1 $and $v_2$ respectively releasing no energy in any other form like sound and heat.
Then I've read that-
intial k.E = ...
- 367
-1
votes
1
answer
121
views
Hand wave-y "derivation" of relativistic momentum [closed]
In lecture, my professor went over a kind of non-rigorous "derivation" (not really a derivation, but more of a demonstration) of the expression for relativistic momentum. However, I don't ...
- 187