Reputation
1,006
Next privilege 2,000 Rep.
Edit questions and answers
Badges
7 11
Newest
 Yearling
Impact
~80k people reached

Feb
1
comment Coefficient of friction and practical experience of sliding
I am comparing laying with sitting on the butt, not standing. Standing is completely irrelevant, for the reasons you mention and also because shoes have much higher friction than jacket (by design). When sitting, the CoM is slightly higher then laying, but low enough to slide without toppling.
Feb
1
asked Coefficient of friction and practical experience of sliding
Jan
27
comment Backyard experiments to falsify the Flat Earth theory
Combining with physics.stackexchange.com/a/26431/6395, this can be improved. Take the unbeliever to the sea shore (no possibly photoshopped pictures) somewhere where they have a watch tower. Wait for a ship to start disappearing below the horizon, then climb to the tower and observe the ship is still visible from there.
Jan
18
comment How am I able to stand up and walk down the aisle of a flying passenger jet?
You don't even need to consider a plane. You are walking on Earth, which rotates with speed up to 1670 km/h (depending on your latitude), orbiting the Sun at nearly 30 km/s (and orbiting the centre of galaxy, but I don't know what that speed is; probably even larger though).
Nov
28
awarded  Yearling
Nov
20
comment Why does rotation simulate gravity if motion is relative?
@Flosculus, because the reference frames rotate relative to each other, the accelerations in them will be different. The differences will imply existence of a centrifugal force for the observer on surface and that implies he is in rotating frame of reference. The observer flying by is not needed; just measuring the centrifugal force at various points on the surface allows determining the axis of rotation and angular speed.
Nov
20
comment Why does rotation simulate gravity if motion is relative?
@JeremyOlson, every universe has an infinite number of reference frames, because reference frame is just a mental construct. However, you need to attach such reference frame to some object to be able to observe laws of physics in it. Now in a universe that only contained one point mass there would be no way to accelerate it, because momentum must be conserved, and no way to spin it, because angular momentum must also be conserved. For both you need the universe to contain multiple particles and then you have enough objects to measure relative speeds of to detect acceleration.
Nov
20
comment Why does rotation simulate gravity if motion is relative?
@Flosculus, it implies there are static axis, but any set of static axis is still equivalent.
Oct
21
answered Does the force between two point charges change when inertial reference frame changes?
Oct
12
comment Why can't helicopters reach mount everest?
@AndyM, also note, that it is the stream velocity orthogonal to the structure that matters, so aircraft use swept wings to delay the effects of reaching speed of sound. Some modern propellers are also curved for the same purpose. But helicopters can't simply use curved blades, because the blades must be precisely balanced as they are tensed by the centrifugal force, but some new helicopters do have blades that are swept a bit forward and then back again near the tip to get some benefit of sweep while keeping the centre of mass where it needs to be.
Oct
12
comment Why can't helicopters reach mount everest?
@AndyM, I did not actually say it is dangerous per se. The problem is that as the flow exceeds speed of sound, the drag raises greatly and the lift drops. So if the rotor blades tips approach speed of sound, they won't be able to accelerate further, may be damaged by the forces and won't deliver more lift anyway.
Sep
28
comment If action equals reaction, how is it ever possible to win in martial arts?
It also matters where the momentum ends up. Many strikes are not intended to hurt, but to throw the opponent out of balance by transferring more momentum than the opponent can pass on to the ground in that direction.
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.