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seen Aug 20 at 20:35

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?
Jun
10
awarded  Teacher
Jun
10
answered How fast do you need to travel to go 35 light-years in 2 (apparent) years?