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6h
comment Why does a ball eventually stop?
Rolling friction is almost always much more important that air drag for a ball rolling. Only at higher velocities will air drag dominate. Since drag goes with velocity squared (until Reynolds number becomes very small) the air drag may slow the ball down but is not dominant just before the ball stops - so it's not responsible for the ball becoming stationary.
6h
comment Why does a ball eventually stop?
You are right that "rolling friction" is a thing - but your explanation doesn't really match the diagram. And the diagram is not yours - can you please provide attribution?
14h
comment How do exercise gyroscopes work?
Are you saying that the exercise gyroscope starts spinning faster ("cause it to accelerate") as you work with it? Can you show a picture of the design?
14h
answered How do Calories (kcal) relate to watts?
15h
comment How to calculate impulse required to move an object vertically upward by given distance
I found a few online videos with the derivation, but they seemed to have some suspicious "download this player" type links which triggers my spider sense that there is a Trojan about to be installed - so I would prefer not to give you the link. If I find something (or decide to do the derivation myself) I will update.
19h
comment When only part of the surface an object is in contact with has friction, what is the normal force I should use?
I looked at your other answer. I agree that in the case of elastic deformation of the substrate / contact interface, there will be a (near) singularity at the corners, but it's not clear to me that the force will be evenly distributed when the rod is sliding with friction on only one corner. Do you agree with me that if there is any friction, the resulting torque will affect the force distribution? Incidentally - it wasn't my downvote...
1d
comment Breakdown of Snell
When the object becomes very thin compared to the wavelength, all bets are off. Photons may simply not interact with the material as each atom has a finite cross section (probability of interaction) - So REALLY thin materials don't quite appear to obey Snells' law. But once the material is thick enough that all incident photons interact, Snells' law works just fine. Quarter wavelength or greater is no problem. Can you give a reference for your assertion that Snell's law is not obeyed?
1d
answered When only part of the surface an object is in contact with has friction, what is the normal force I should use?
1d
comment When only part of the surface an object is in contact with has friction, what is the normal force I should use?
I think this is wrong. If the entire rod is in contact with the surface, then the normal force should be apportioned in proportion to the contact area - not evenly divided between "has friction" and "does not have friction". Although in reality, the height of the object should matter. As the friction generates torque, the normal force on the leading edge will increase...
1d
comment Humans Voice Frequency?
Yes that's right.
1d
comment Circular Waveguide (for dominant mode)
Would this help? rfcafe.com/references/electrical/circular-waveguide-modes.htm
1d
answered Humans Voice Frequency?
1d
comment Humans Voice Frequency?
I'm voting to close this question as off-topic because it is about physiology of speech, not physics.
1d
comment Humans Voice Frequency?
People have a voice print which is a combination of the spectral content of their voice, together with how they pronounce different vowels, speed, etc. It is used for voice authentication - usually one step in complex multi-factor authentication. But that's not really a physics question. See for example this link
1d
comment Why build so big sarcophagus in Chernobyl instead another alternative?
Imagine you are the person opening the sarcophagus in order to demolish it. What is protecting you from radiation until the new one is built?
1d
answered In the photoelectric effect, what happens to the electron if the work function is too low?
1d
comment How to calculate impulse required to move an object vertically upward by given distance
@user2617526 - I added some more math, but not a complete derivation.
1d
revised How to calculate impulse required to move an object vertically upward by given distance
added 2536 characters in body
1d
comment How to calculate impulse required to move an object vertically upward by given distance
See hyperphysics.phy-astr.gsu.edu/hbase/mechanics/quadrag.html for the correct treatment
1d
comment How to calculate impulse required to move an object vertically upward by given distance
The velocity will not be constant - it will change throughout the trajectory. There is a closed form solution for a projectile with quadratic drag - I will look it up and add it to my answer. May take me a little time...