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Jul
24
comment Will computer fan rotate slower if one makes impeller heavier?
That wasn't your argument. I am aware that if mju doesn't change then obviously a higher loading on the bearings would increase friction. But that wasn't what the OP said. The OP said "bearing friction do not change". Nor was it what you said.
Jul
24
comment Will computer fan rotate slower if one makes impeller heavier?
I disagree with your analysis. The tensor of Inertia only affects the fan when the angular momentum is changing. Assuming that the fan gets to a steady state, then by definition the angular momentum ISN'T changing.
Jul
8
comment How can I estimate the cooking time of a roast?
160°F ? What kind of Physicist are you? Either use Kelvins or Rankines!
Jul
6
comment Does stopping the same bike and rider at the same velocity with the front brake require less energy than the back brake?
"For motorbikes, it is recommended that you use the front brake more heavily to prevent skidding" This is true of bicycles as well. Unfortunately the average skill level of cyclist is far below that of the average motorbike rider.
Jun
29
comment How can a material conduct heat but not electricity
The logical fallacy here is that free electrons carrying heat does not mean heat is carried by free electrons.
Jun
15
comment How would the laws of nature behave if we reversed time?
@Ooker What Ian is saying is that the Newtonian laws of motion (when neglecting friction/air resistance and co-efficient of restitution) are invariant under time reversal (are the same). These two effects are also the first casualties in Spherical Sheep in a Vacuum style Physics.
Jun
10
answered What is a conservative force?
May
26
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.