1,302 reputation
1126
bio website dotancohen.com
location
age 37
visits member for 3 years, 8 months
seen 7 hours ago

Apr
29
comment Does a truck stop faster if the stack on the back of truck is stable or if it moves forward?
@WetSavannaAnimalakaRodVance: You guys have semitrailers with an odd number of wheels? Or is the steering wheel counted in there too?
Apr
27
revised Is there any disadvantage to sending rockets straight up?
Correct accidental term swap
Apr
27
suggested approved edit on Is there any disadvantage to sending rockets straight up?
Mar
20
awarded  Inquisitive
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
9
awarded  Popular Question
Feb
6
revised Why do most formulas in physics have integer and rational exponents?
added 6 characters in body
Feb
5
revised Why are there more vertical takeoff than horizontal for spacecrafts?
added 514 characters in body
Feb
5
answered Why do most formulas in physics have integer and rational exponents?
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
14
awarded  Notable Question
Dec
13
comment Is a block of cotton heavier than a block of iron?
@Hypnosifl: Answer edited to address your comment. Thank you.
Dec
13
revised Is a block of cotton heavier than a block of iron?
Address comment
Dec
13
answered Is a block of cotton heavier than a block of iron?
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!