All Questions
276
questions
20
votes
8
answers
4k
views
Geometrical construction for Snell's law?
Snell's law from geometrical optics states that the ratio of the angles of incidence $\theta_1$ and of the angle of refraction $\theta_2$ as shown in figure1, is the same as the opposite ratio of the ...
- 267
3
votes
2
answers
412
views
sum of N light sources
[sorry for the bad English]
I am fond of astronomy and environment.
I want to try to make a "light pollution map" but I haven't my satellites... so I use as approximation of light pollution the cities'...
- 136
85
votes
9
answers
68k
views
What is the meaning of the third derivative of a function at a point
(Originally asked on MO by AJAY.)
What is the geometric, physical, or other meaning of the third derivative of a function at a point?
If you have interesting things to say about the meaning of the ...
- 1,133
2
votes
1
answer
534
views
Temporal aberration. Shape of telescope mirror large enough that light transit time is significant
Suppose a parabolic mirror of a telescope is large enough (or equivalently that the camera exposure time is short enough) that you need to take into account the transit time of the light signal from ...
- 203
3
votes
4
answers
5k
views
Given a radius and velocity calculate position of an aircraft banking to make a turn
I have a radius, R, for an aircraft traveling at velocity, V. If we start at point, (X,Y), ...
- 391
5
votes
1
answer
981
views
Center of mass of an $n$-hemisphere
Related to this question.
Note that I'm using the geometer definition of an $n$-sphere of radius $r$, i.e.$ \\{ x \in \mathbb{R}^n : \|x\|_2 = r \\} $
Suppose I have an $n$-sphere centered at $\bf ...
- 2,580