All Questions
9
questions
3
votes
2
answers
236
views
Centroid and "Centre of mass"
I thought that the centroid was also the point at which the area in all directions was net 0. Aka area above the cenrroid was the same area as below.
But for a triangle everything I can see seems to ...
- 165
2
votes
1
answer
73
views
How to find the side of the triangle?
I need to find the value on the $v_{1}$ side of the triangle, the book's answer is $v_{1} = V cos(\psi) + v'_{1} cos (\theta - \psi)$, but I couldn't understand how you get to that result. I used the ...
- 81
1
vote
0
answers
51
views
What geometric/trigonometric reasoning was used to deduce that $\theta_1 = \theta_0 - \theta$ and $(-\theta_2) = \theta_0 + \theta$?
I have the following figure from Fundamentals of Photonics, Third edition, by Saleh and Teich:
The accompanying explanation says the following:
The angle $\theta_2$ is negative since the ray ...
- 4,322
0
votes
1
answer
152
views
Deducing angle in equilateral triangle by the formula $\phi_2 = \alpha - \phi_1$
I have the following equilateral triangle:
In the following picture of the same equilateral triangle, the dotted lines are the normals to the surfaces:
Since this is an equilateral triangle, we know ...
- 4,322
0
votes
1
answer
1k
views
Formula for the diameter of an emerging beam
I have the following problem:
A thin beam of white light with negligible radius is incident at $50.0^\circ$ on a $10.0 cm$ thick slab of clear plastic. The index of refraction for red light in this ...
- 4,322
0
votes
1
answer
629
views
Deducing angles in an equilateral triangle with normals to surfaces
I have the following equilateral triangle:
In the following picture of the same equilateral triangle, the dotted lines are the normals to the surfaces:
Since this is an equilateral triangle, we know ...
- 4,322
1
vote
1
answer
65
views
Understand geometry calculation about light interference
My question is about interference of light through a thin layer of some material. This image shows how one can easily calculate using basic geometry whether you will have positive/constructive or ...
- 11
0
votes
2
answers
42
views
How do I write this force in terms of another variable? [closed]
I have the tidal force, $\vec{F}=-GMm(\frac{\hat d}{d^2}-\frac{\hat d_0}{d_0^2})$ where:
How do I express the force in terms of $\theta$? I'm given that $\vec{r}=R(\cos(\theta),\sin(\theta))$. I'm ...
- 1,587
0
votes
1
answer
3k
views
Finding angle on an inclined plane
How can I go about finding the angle, theta, in this Physics problem?
As you can tell, the right-most triangle is a simple 30-60-90 triangle, so above the right angle is a 60deg angle. Then the ...
- 391