In introductory mechanics, the momentum of a particle is its mass times its velocity. In electrodynamics, the momentum of a field is proportional to the cross-product of the electric field with the magnetic field. In special relativity, momentum is generalized to four-momentum.
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Confusion between the de Broglie wavelength of a particle and wave packets
So I learned that the de Broglie wavelength of a particle, lambda = h/p, where h is Planck's constant and p is the momentum of the particle. I also learned that a quantum mechanics description of a ...
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269 views
physics- momentum ( a space question) [closed]
An astronaut is conducting repairs on a satellite 50.0m from a space shuttle. Her mass is 120kg (including space suit) and she is using a 0.5kg spanner. She realises that she only has 5 minutes oxygen ...
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544 views
Could a fish in a sealed ball, move the ball?
If you had a glass ball filled with water, completely sealed and containing a fish, could the fish move the ball?
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1answer
205 views
Uncertainly Principle in orthogonal directions
The Heisenberg Principle states that for each direction, $\Delta x\cdot \Delta p_x \ge \hbar , \Delta y\cdot \Delta p_y \ge \hbar$ and $\Delta z\cdot \Delta p_z \ge \hbar$.
But, can anything be said ...
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256 views
Does the rotational speed of a planet consistently become faster and faster given that there are no conflicting events? [closed]
Does the rotational speed of a planet consistently become faster and faster given that there are no conflicting events?
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652 views
A Basic Question about Gravity, Inertia or Momentum or something along those lines
Why is it that if I'm sitting on a seat on a bus or train and its moving quite fast, I am able to throw something in the air and easily catch it? Why is it that I haven't moved 'past' the thing during ...
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1answer
249 views
What is the linear momentum of an EM wave in a medium?
In free space, the linear momentum density of an EM wave is given by the Poynting vector $\vec S$ over the speed of light squared, $\vec g=\frac{\vec S}{c^2}$.
In a medium, $S$ is generally not ...
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1answer
254 views
Finding the mass of bed/Patient
One of my friends has a problem and we don't know how to get this done,
We want to to know the mass of a patient who is laying on a bed. One scales was put under the foot of a bed and weighed 232kg ...
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1answer
114 views
Do $x$ and $Q^2$ associate with particular directions in the infinite momentum frame?
In deep inelastic scattering, you describe a collision using the variables $Q^2 = -q^2$ (probe virtuality) and $x = Q^2/2p\cdot q$ (Bjorken x, parton momentum fraction). Now, I seem to remember ...
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3answers
2k views
Is the giant Newton's cradle in the Kit-Kat ad feasible?
Apologies in advance if this is too basic a question for physics.stackexchange. I don't want to dumb down this venerable institution. :)
My wife and I just watched this TV ad for Kit-Kat where a crew ...
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2answers
481 views
Tricky spring on a surface question
I have this relative simple-looking question that I haven't been able to solve for hours now, it's one of those questions that just drive you nuts if you don't know how to do it.
This is the scenario:
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