Rahul
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 Dec 16 comment Is it possible to blur an image in such way that a person with sight problems could see it sharp? Those constraints (positivity, finite size) mean that you can't reproduce the image perfectly, but you can still get a pretty good approximation: cs.purdue.edu/homes/igarciad/p/2015_TOG/2015_TOG.html Dec 16 comment Is it possible that a person with myopia will see a blurry picture as normal? Isn't this a duplicate of "Is it possible to blur an image in such way that a person with sight problems could see it sharp?" Jul 12 comment Why is the surface of the Moon white? @Rob: There is no such thing as grey light, but there is such a thing as a grey object. It is perfectly possible for reflectance, which is a fraction, to be lower than 100%. Mar 27 comment How small does sand have to be to get wet? @Adam: The order-of-magnitude estimate is $h \approx 10^{-5}/r$ in meters. For reference, sand grains are about $10^{-4}$ to $10^{-3}$ meters in diameter. Sep 14 comment Is the Moment of Intertia of A Thin Rod equal to The Moment of Intertia of a thin Strip? I imagine a strip as a rectangle with a large length, a small width, and a negligible thickness. Perhaps this is different from what you consider a strip. Sep 14 comment Is the Moment of Intertia of A Thin Rod equal to The Moment of Intertia of a thin Strip? You haven't said whether the width of your thin strip is also negligible. May 13 awarded Nice Answer May 12 awarded Yearling Feb 8 revised What justifies dimensional analysis? added 140 characters in body Feb 8 revised What justifies dimensional analysis? deleted 1775 characters in body Feb 8 answered What justifies dimensional analysis? Feb 5 comment Looking for the actual reason of refraction explained precisely without analogies No one has mentioned Huygens' principle yet? It convinced me when I was 15 years old. Nov 18 awarded Commentator Nov 18 comment I'm having trouble understanding the dimensions of this falling body problem Anyway, yes, the $5$ has dimensions of force per unit velocity = $\mathrm{N\:s\:m^{-1} = kg\:s^{-1}}$. This is no more unusual than if I were to say a thermometer's mercury level rises 2 millimeters whenever the temperature goes up by a degree Celsius, giving units of $\mathrm{m\:K^{-1}}$. Oct 29 awarded Editor Oct 29 revised What does the wind speed have to be to blow away a person? fixed links Oct 29 suggested approved edit on What does the wind speed have to be to blow away a person? Jul 24 comment Can one make a ball rotate around a vertical axis using only a combination of horizontal axis rotations? What is the exact text of the problem? Jul 24 comment Can one make a ball rotate around a vertical axis using only a combination of horizontal axis rotations? What is the model of "pushing" here? I would assume it means applying an impulse to instantaneously change the angular velocity, $\omega_\text{after} = \omega_\text{before} + \Delta \omega$, but then the answer is a trivial "no". Jul 24 comment Can one make a ball rotate around a vertical axis using only a combination of horizontal axis rotations? By the way, this is known as a kugel ball. Question: by "turn around the vertical axis" do you mean produce a net rotation or impart an angular velocity about the vertical axis?