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Mar
19
comment Could we send a man safely to the Moon in a rocket without knowledge of general relativity?
I suppose that special relativity would counter a portion of the difference, my guess would be about 10-20%, considering the TLI speed of over 10 km/sec.
Mar
2
comment Why doesn't NASA use RAMJET rockets to get into space?
Related discussion on Space.SE
Mar
2
comment Why doesn't a cigarette lighter generate thrust?
@lemon: Did you cause this mess?
Feb
5
comment Why do most formulas in physics have integer and rational exponents?
This answer hits the nail on the head at the beginning: the reason is that the relationships in question are all linear. Why are they linear relationships? For the geometrical measurements, the answer is proportional scale. For the physical measurements, the answer is (usually) conservation of energy.
Dec
31
comment Does a ball resting on the ground have acceleration?
@WetSavannaAnimalakaRodVance: Thank you for clarifying the meaning, via the etymology, of the term "proper". That makes understanding some concepts so much easier!
Dec
19
comment Why isn't length contraction permanent even though time dilation is?
The length of space passed is in fact permanently contracted. Without loss of generality, consider a particle moving at C. For it the space passed contracted to 0 and the time passed was 0. If the space travelled were not permanently contracted, the particle would not be permanently at the new location after 0 time. Note that this does not imply that the distance can be traversed again in its contracted state.
Dec
13
comment Is a block of cotton heavier than a block of iron?
@Hypnosifl: Answer edited to address your comment. Thank you.
Dec
2
comment Cooling a satellite
@HotLicks: EVA suits sublimate ice into vapor as a cooling method. I do believe that the vapor is recovered, though I'm not sure. A recent mishap with that system had water collecting inside a space suit, sending the astronaut rushing back to the ISS airlock.
Dec
1
comment Must Matter Particles Have A Hard Edge?
Thank you for this wonderful question, by the way. The answers generated are terrific and really cover the topic from all angles. Welcome to Physics.SE!
Dec
1
comment Must Matter Particles Have A Hard Edge?
It actually is smeared out, until it must interact (i.e. transmit a force)!
Nov
28
comment Why does rotation simulate gravity if motion is relative?
Arguably, this question and Draksis' link provide the background needed to understand exactly why we are still looking for a way to reconcile gravity with GR.
Nov
24
comment Why aren't there spherical galaxies?
@Ruslan: The OOrt cloud is such an example.
Nov
20
comment If your hair was on fire and you entered a vacuum, could you outlast the fire?
+1 for the information regarding the biological damage, which is missing in many of the other excellent answers.
Nov
2
comment What are Stephen Hawking's main contributions to research-level physics?
You mention that you do not have the time to read 190 research papers. There is your answer. Hawking wrote or contributed to 190 research papers. That is quite the accomplishment.
Oct
14
comment How did Kelvin make this fascinating calculation?
This is such a beautiful answer, I wish that we could star answers as opposed to questions.
Oct
1
comment How empty of fuel are spacecraft booster rockets typically?
@David: Replace "half kilo" with "small but not infinitesimal" and "ipod" with "dirt, pollen, personal items, lice, urine still in the bladder, bird poop on the craft exterior, and other things that are not easily accounted for mass directly".
Sep
10
comment Should I abandon my thought experiment about time?
Note that watching a natural clock (the orbits of the moons of Jupiter) approach and recede (as the Earth and Jupiter got closer and further away) was one of the hints that led to the developments that led to the understanding of the speed of light, and also of the dimensions of the solar system.
Jul
25
comment Calculate loudness of sound: why am I getting contradictory answers?
I see now where my confusion was. Thank you for showing the maths explained, and especially for the comment which explains why the perceived value to my ears is so much lower that what the maths make us expect.
Jul
25
comment Calculate loudness of sound: why am I getting contradictory answers?
Thank you. You certain understand how to phrase the ideas into terms that are easier to digest, and to address the points of confusion.
Jul
25
comment Calculate loudness of sound: why am I getting contradictory answers?
That wikibook is terrific, thank you!