Questions tagged [momentum]
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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If photons have no mass, how can they have momentum?
As an explanation of why a large gravitational field (such as a black hole) can bend light, I have heard that light has momentum. This is given as a solution to the problem of only massive objects ...
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Can we theoretically balance a perfectly symmetrical pencil on its one-atom tip?
I was asked by an undergrad student about this question. I think if we were to take away air molecules around the pencil and cool it to absolute zero, that pencil would theoretically balance.
Am I ...
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Why does a billiard ball stop when it hits another billiard ball head on?
(I'm repeating myself a lot here, but it's because I want to make my confusion clear.)
If 2 billiard balls are the same exact mass, and one hits another stationary one head on, I have heard that the ...
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Does throwing a penny at a train stop the train?
If I stand in front of a train and throw a penny at it, the penny will bounce back at me.
For the penny to reverse its direction, at some point its velocity must go to zero. This is the point it hits ...
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How can momentum but not energy be conserved in an inelastic collision?
In inelastic collisions, kinetic energy changes, so the velocities of the objects also change.
So how is momentum conserved in inelastic collisions?
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In substances where light is slowed down, is its momentum lessened and if so, how does it speed up again when emerging from that substance? [duplicate]
I think in some media, light can be significantly slowed down; but even if only slightly, where would the momentum go when the light slows down and where does it get the extra momentum when it leaves ...
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Can a Skydiver Land On a Large Slide and Survive?
Please forgive my lack of artistic ability, but here's my question:
Consider that a skydiver, without using his parachute, were to fall exactly parallel to a giant curved slide that starts at $90\,^\...
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Why does the speed of a ping pong ball increase when the space in which it can bounce decreases?
I was playing table tennis the other day when I my ball fell off the table. I placed my paddle above it in order to slow it down, and then I brought the paddle to the ground so that the ball would ...
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Can kicking a falling phone save it from shattering?
So I saw this tip
but I don't think this is true, it would be that your leg or shoe is more flexible than a hard floor so the momentum change would be slower right?
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For collision, physical contact is not a necessary condition. Why?
In my textbook, it is written that
"For collision, physical contact is not a necessary condition".
How can collision occur without physical contact? If there is no physical contact, then there ...
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Newton's 3rd law... hitting drywall (which I break) vs hitting a brick (which breaks me)?
According to the Third Newton's law of motion:
For every action there is an equal and opposite reaction.
So, I understand that if I hit a brick wall with $50\, \mathrm{lbs}$ of force, the brick ...
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How to escape the center of a room without gravity? [closed]
Imagine you're an astronaut on the International Space Station and your fellow astronauts played a prank on you by taking all your clothes and putting you in the center of a module so that you cannot ...
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What's wrong with this derivation that $i\hbar = 0$?
Let $\hat{x} = x$ and $\hat{p} = -i \hbar \frac {\partial} {\partial x}$ be the position and momentum operators, respectively, and $|\psi_p\rangle$ be the eigenfunction of $\hat{p}$ and therefore $$\...
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What's the deal with momentum in the infinite square well?
Every now and then a question comes up about the status of the momentum operator in the infinite square well, and while we have two good answers on the topic here and here, I'm generally not satisfied ...
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What is momentum really?
The Wikipedia article on momentum defines momentum as in classical mechanics:
… momentum is the product of the mass and velocity of an object.
However, an electromagnetic field has momentum, which ...
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