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comment In a Dyson shell, could centripetal force act as gravity?
A 'Dyson cylinder' would work, but then different parts of the inner surface would be at different distances from the sun. It'd make for interesting weather.
comment What is the acceleration at the top most point of a ball’s journey vertically upward?
Imagine you're in space and your ball has a little rocket engine. You throw the ball away, and the rocket engine is thrusting to return it to you. At the farthest point, before it reverses direction, it briefly stopped moving; but it's clear that the engine is continuously thrusting, accelerating toward you at the same rate. It's because of the constant acceleration that the velocity passes through zero and reverses.
comment When I boil a kettle, what stops all the water from turning (exploding!) in to steam in one go once it reaches 100°C?
I think this is missing the key component of explaining why this doesn't happen all at once. Yes, there's additional energy needed for the phase transition, but why isn't that additional energy evenly distributed? (I think it's just due to factors causing uneven heating, but it needs to be addressed.)
comment relationship between voltage and current
If you hold power FLAT and increase current, voltage would have to decrease. Similarly, if you hold resistance flat and increase current, voltage would have to increase. In practical terms, to hold power flat while you decrease voltage, you would have to be adjusting resistance down to increase current.
answered Rate of change in size: Moving Objects
comment What would it be like “inside” a star?
@DevSolar - Generally, radiation falling on an object changes inversely to the square of the change in distance. Move something twice as far away, the radiation drops to 1/4. Move something half as far away, the radiation increases by 4. Move something to 1/500 the distance, the radiation increases by 500^2 = 250,000 times. Note that the actual temperature doesn't scale linearly... the hotter something gets, the faster it radiates heat away. FYI, Mercury is .387 AU from the sun (Earth is 1 AU), so each square meter on Mercury receives 1/(.387^2) = 6.7 times as much radiation as Earth.
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comment How would we see a near-lightspeed object emitting light?
Would this affect other forces besides electromagnetism? Would an object traveling near light speed relative to me exert weakened nuclear, or even gravitational force on me as it passed?
comment Why does the universe follow the uncertainty principle?
I've seen an argument that the presences of the uncertainty principle allows the elimination of some possible paradoxes and contradictions (of the Zeno's Arrow type).
comment Why does a helium filled ballon move forward in a car when the car is accelerating?
Maybe an easier way to envision the forces involved would be to use a bottle filled with water except for one air bubble. Then, it makes intuitive sense that the bubble moves in opposition to the acceleration.
comment Why doesn't light kill me?
Wow, this question got protected fast. Guess I'll just add a comment... Another perspective is to look at dilution. At the surface of the sun, of course, the light intensity would vaporize you instantly. But if you do some geometry, you can see that as the spherical shell of light expands, by the time it's reached the earth it's covering an area close to 50,000 times larger... reducing the intensity at any point by 50,000 times.
comment Are quantum mechanics and determinism actually irreconcilable?
Some people see the many-worlds interpretation of quantum mechanics as preserving determinism, since there is no random waveform collapse as such in that theory; instead, the only 'random' factor is our subjective perception of which universe we are in (which isn't really random, since all other universes can ask the same question).
comment Membrane that allows liquid to pass only when forced under pressure
I'm imagining a rubber membrane, with moderate thickness and many small puncture holes punched in it. The holes would be small enough to block flow, until pressure increase and the whole membrane swells and thins. Never seen anything like that, though.
comment Rotation, cats landing on their feet, and conservation of angular momentum
It would. The 90 degree arc when it's fully extended contributes far more angular momentum than the 90 degree arc backwards does when it's near your center of gravity.
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