0
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4answers
89 views

Dot product of vector and its derivative with respect to time? How does $L \cdot\frac{dL}{dt} = \frac{1}{2}\frac{d(L^2)}{dt}$? [closed]

How does: $$L \cdot\frac{dL}{dt} = \frac{1}{2}\frac{d(L^2)}{dt}$$ where L is a vector (I dunno how to make it bold in the equation). How do they reach to this right hand side equation? And what is ...
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1answer
59 views

What does this sort of notation mean?

I'm revising for my exams at the moment and am seeing this notation everywhere Can anyone tell me what these mean?
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1answer
4k views

What does y with a line over it represent?

I've been asked to complete this chart and have never come across this symbol before, nor can I find anything about it on google: http://postimage.org/image/oe7hb9cy3/ What does the y with the line ...
1
vote
1answer
361 views

Symbol for dashpot/damper (in a harmonic oscillator)

In diagrams that contain the dashpot symbol, sometimes the mass is attached to the "interior" end of the dashpot, other times the mass is attached to the "base" end. For example, consider the ...
1
vote
1answer
65 views

What is $k_B$ in the context of this question?

Answering the following question 1000 atoms are in equilibrium at temperature T. Each atom has two energy states, $E_1$ and $E_2$, where $E_2 > E_1$ . On average, there are 200 atoms in the ...
1
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1answer
287 views

Rocket drive and conservation of momentum

I am currently reading through some lecture notes of Physics 1 and in a chapter about the dynamics of the mass point, there is an example covering the rocket drive. Let $v$ be the velocity of the ...