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Aug
14
comment Flat throw vs 45 degree throw of a ball
I would suspect that the fact that you are usually throwing overhand also has something to do with it, because when throwing flatter the ball leaves the hand later and therefore you apply force to it longer for greater total impulse.
Jul
22
awarded  Civic Duty
May
18
comment Why electric field inside charged conductor is zero in the electrostatic case?
@Algohi: In a conductor the charge does not have to move as a unit. It can split and disperse and it will disperse so that the Gauss' law holds. (That's why I wanted to mention ignoring quantum effects; charges are considered infinitely divisible).
May
18
comment Why electric field inside charged conductor is zero in the electrostatic case?
@RossMillikan: It ignores any quantum effects though, doesn't it? If there are just four elementary charges, they shouldn't be able to redistribute themselves (but at that scale treating the conductor as “solid” is no longer substantiated either).
Apr
18
comment How can an object move from point A to point B?
@Feynman: No, we say a series of finite steps is completed when the last step is completed. For infinitesimal steps it does not apply.
Apr
17
comment How can an object move from point A to point B?
@Feynman: “But, for every action to complete, there must be last step, isn't it?” No, it does not. The sequence only has to have a finite sum (size). (i.e. I am responding to your premise, not the point).
Apr
17
comment How can an object move from point A to point B?
@Feynman: No, when the steps are infinitely divisible, there is no last one, because the last step is always divisible in two, one of which is “laster”.
Apr
16
comment Why doesn't light, which travels faster than sound, produce a sonic boom?
@TheBlackCat: It does not. But the answer says it does not interact, without qualifying it. And it needs to be qualified.
Apr
16
comment Why doesn't light, which travels faster than sound, produce a sonic boom?
Light is also a stream of photons. It also does interact with air. Not just strong pulses; any light does (it scatters and gets absorbed).
Apr
10
comment Are there any scales other than temperature that have different zero points?
Especially if you consider indicated and pressure altitude as pressure and density altitude as density, the quantities they actually measure.
Feb
27
comment Freefall into snow
@Lodewijk: Actually, you can estimate the profile of the acceleration. It would be increasing proportionally to how the snow below them gets compressed.
Jan
28
comment Will we ever be able to view the past?
However if we need to install the mirror, installing mirror 100 lightyears from Earth is going to take at least 100 lightyears, so we can't ever watch our actions from before we decide to install it. And we didn't do it yet, so we won't be able to view actions that are already past.
Jan
27
comment Throwing an object around the Earth. Is it possible?
And the other point is that almost any shape can produce some lift. And javelin is actually pretty decent lifting body.
Jan
27
comment Throwing an object around the Earth. Is it possible?
Orbits are ellipses, but trajectory with perigee could be out of atmosphere for most part and still not pass through the ground at any other point (I am not sure whether it was included in what you meant by “surface-grazer”, but it does not really graze the surface except at the point of launch.
Dec
19
revised Would an airtight box filled with air act the same way to 1 bar of water pressure as the same box vacuum-sealed at atmospheric pressure?
tension stress also only depends on the difference
Dec
19
comment Would an airtight box filled with air act the same way to 1 bar of water pressure as the same box vacuum-sealed at atmospheric pressure?
@JerrySchirmer: Buoyant force depends on volume of displaced fluid and density of that fluid. In one case water is being displaced, in the other case air is. Therefore the buoyant forces are different.
Dec
19
answered Would an airtight box filled with air act the same way to 1 bar of water pressure as the same box vacuum-sealed at atmospheric pressure?
Dec
19
comment Would an airtight box filled with air act the same way to 1 bar of water pressure as the same box vacuum-sealed at atmospheric pressure?
@JerrySchirmer: The buoyant force would definitely be different, because water is much denser than air.
Nov
28
awarded  Good Answer
Nov
28
awarded  Yearling