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2d
comment in Newtons 3rd law, where does the second body get its energy to react?
I think you have confused force and energy. If I am sat on a chair (which I am currently doing). Then the chair is pushing me up, whilst I am pushing down. No energy transfer is happening as no change is occurring.
May
23
comment What would be the rate of acceleration from gravity in a hollow sphere?
Why is this answer more popular than the Newton's Shell Theorem answer?
May
17
comment How electrons move so fast in a electric circuit?
@reirab what is this orbital velocity you speak of?
May
17
comment Question on normal force and static friction
The point is that friction is a retarding force. It only exists to oppose another force. Therefore there is are two limits to friction, (normal contact force * coefficient of friction), and (sum of other forces acting on the object).
May
14
comment What will happen if a ball of ice with the mass of sun is thrown into the sun?
At the energies that this situation provides, I doubt there is time for thermalization of anything.
May
13
comment What will happen if a ball of ice with the mass of sun is thrown into the sun?
@RobJeffries you are right. Messed up on the calc on KE. Still, the energies here are more than enough for any purpose.
May
12
comment What will happen if a ball of ice with the mass of sun is thrown into the sun?
I suspect you have underestimated the inelastic collision effects. With 1Mm/s, we would not be in the relativistic realm quite yet, but still the effects would be spectacular nevertheless. We are talking about the equivalent of 0.3% Solar mass undergoing spontaneous annihilation or approximately 200 type 1a supernovae.
May
5
comment Is possible to create water?
Creating water would require Baryogenesis, which is as far as we know, impossible (ignoring the fact that water exists, and therefore it should be possible)...
May
5
comment Paradox in special relativity
@PyRulez a relativistic projectile being released upon an insect? Unless that "everyday material" was massless and in a vacuum, I believe we would see Relativistic Kill Vehicle like baysplosions. what-if.xkcd.com/1
May
3
comment Why are high energies needed in collision experiments?
You actually have it the wrong way round. Particle Physics is often called High Energy Physics. We use particle accelerators because its the easiest way to get (kinetic) high energies. It is also possible to use nuclear reactors and decaying isotopes, but it much harder to get the energies we are experimenting with today.
Apr
26
comment Can you ever exert more downwards force than your weight?
TLDR: You could jump up and down on top of the post and you would exert F > mg (at the instance you land). youtube.com/watch?v=shqaQopEmhY
Apr
13
comment Can you heat something in AL foil using IR?
@RickPH If you didn't already notice, Aluminium is a metal. A metal reflects most EM radiation frequencies well because of the wide conduction band they support. In short, THERE IS NO SWEET SPOT.
Apr
13
comment Can you heat something in AL foil using IR?
In fact Aluminium foil is often used to do the opposite of what you are asking OP.
Apr
3
comment Is speed of propeller-driven airplane limited by the speed of sound?
@tpg2114 I disagree with you on one significant point. You would see loss of lift not just at the tips, but the entire blade. Loss of lift STARTS at the tips (since they are moving the fastest). But by the time you are in supersonic airflow, all of the blade is moving through the air faster than the speed of sound (even if the blades stopped rotating). However, supersonic blades do still generate lift, as the Tupolev Tu-95 demonstrates.
Mar
24
answered Can an electric current's magnetic field be represented by a magnet/magnets?
Mar
13
comment Is it possible to sail “close hauled” with a solar sailship?
@jameslarge hence when I am teaching I use the term "lateral resistance" which I believe is the RYA term, as opposed to "keel action" which could also refer to the righting action of the weight. Oh forgot to say, I'm a sailing instructor as well as a master in physics.
Mar
12
comment Is it possible to sail “close hauled” with a solar sailship?
@jameslarge a keel in sailing parlance is a weighted foil under the boat. Even if you extend it to non weighted, I am a board sailor... We definitely don't have a keel, nor do kiteboards.
Mar
12
comment Is it possible to sail “close hauled” with a solar sailship?
Minor correction, not all sailing boats have keels (for example cats and dinghies). The interaction is called "lateral resistance".
Mar
11
comment Is there an infinite amount of wavelengths of light? Is the EM spectrum continuous?
@MSalters it merely means that there is a countable number of inertial frames. If this were the case, it would imply that there were a countable number of energy levels/momenta (for inertial frames), which would certainly produce a self consistent set of rules. As a countable number of energy level/momenta would give rise to a countable number of wavelengths. I suspect we want a QFT expert to answer this one without handwavey arguments.
Mar
9
comment Does coffee cool faster than tap water?
@VolkerSiegel assuming that the particulates thermalise in a time that is insignificant to the bulk cooling of the water.