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Aug
17
revised Is there a way to fill Tank 2 from Tank 1 through Gravity alone?
reupload image from imageshack to stack.imgur before it gets replaced by ads; see http://meta.stackexchange.com/q/263771
Aug
13
comment Can a Skydiver Land On a Large Slide and Survive?
See also: ski jumping.
Aug
2
comment What is the smallest distance possible between two stars?
en.wikipedia.org/wiki/Contact_binary
Jul
30
comment Conical train wheels
Also, I'm pretty sure the center-of-mass argument is backwards. It really doesn't matter whether the CoM moves left or right; what matters for stability is whether it moves up or down, and that's not so obvious from the geometry. (In particular, it depends on the curvature of the wheel surfaces, not just on their slope.) But, of course, the wheel radius effect described by @Kyle probably dominates this anyway.
Jul
23
awarded  Yearling
Jul
15
awarded  Nice Answer
Jul
14
revised Why are expressions such as $\operatorname{ln}T$ used in thermodynamics where $T$ is not dimensionless?
copy comments into answer
Jul
12
answered Why does medium not affect the frequency of sound?
May
13
answered What will happen if a ball of ice with the mass of sun is thrown into the sun?
Apr
29
comment Does a truck stop faster if the stack on the back of truck is stable or if it moves forward?
Short answer: If the stack slides, the truck will stop faster, but the stack will stop slower. Depending on what the stack consist of, that may or may not be desirable.
Apr
24
comment Paradox in applying Newton's second law
Why the hidden spoilers?
Apr
1
revised Does the microgravity environment in highly elliptical orbits differ from circular orbits?
added 825 characters in body
Apr
1
answered Does the microgravity environment in highly elliptical orbits differ from circular orbits?
Apr
1
comment Why doesn't light affect a compass?
Technically, light does cause (bits of) the needle (mostly, the electrons) to wiggle at around 400-800 THz, which is why we can see it in the first place. If it didn't interact with visible light at all, it would be totally transparent.
Mar
2
comment Why doesn't a cigarette lighter generate thrust?
The combustion will also generate some minimal thrust, since it will heat the gas, causing it to expand, and some of that expanding gas will push against the lighter. Still, the combustion geometry is very poor (and the amount of fuel minimal anyway), so you won't get much thrust out of it.
Jan
21
comment Is there a thermodynamic limit on how efficiently you can solve a Rubik's cube?
@MarkEichenlaub: The scrambled cube has about $2^{65}$ possible states; the solved one has only one. On the microscopic level, physics is reversible, so when the cube is solved, the information needed to reverse the solution and reconstruct the original scrambled state from the solved one must go somewhere. That means it either has to be stored in some part of the system, or emitted from it (as heat).
Jan
6
comment What does 1714 mean in hydraulics?
@imallett: If you consider radians dimensionless, then degrees are also dimensionless, with the conversion factor $1\text{ degree} = \frac{\pi}{180} \approx 0.0174533$.
Jan
3
comment Why are porcelain teeth strong?
@Jez: If you hit your teeth "even lightly with a hammer", you'll probably break some or knock them off. (Note: Please do not attempt to test this.)
Dec
27
revised Trying to show that the current is conserved
add \newcommand so the math will show up right even if viewed without the question
Dec
27
revised Trying to show that the current is conserved
fix extra whitespace at top due to \newcommand