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Jul
24
revised Understanding speed distributions: Average speed, RMS speed from a graph?
edited body
Jul
24
answered Understanding speed distributions: Average speed, RMS speed from a graph?
Jun
26
comment Cylinder inside a cylinder - moment of inertia
@NowIGetToLearnWhatAHeadIs I like the argument that the cylinder moves with speed $v = \left(R-a\right) \dot{\theta} = a \dot{\phi}$. Also, if you consider the case $a = R/2$, you can see that the small cylinder will make a single revolution, which agrees with your expression, but not mine.
Jun
26
comment Cylinder inside a cylinder - moment of inertia
I don't see how $\theta = a \phi / \left(R-a\right)$ is right. Consider the case where the small cylinder makes a full revolution within the big cylinder: $\theta \rightarrow \theta' = \theta + \Delta \theta = \theta + 2\pi$. $\phi$ should then increase by $\Delta \theta \times$ the ratio of the circumferences: $\phi \rightarrow \phi' = \phi + 2 \pi R / a$. This is precisely what $R d\theta = a d\phi$ gives.
Jun
25
comment Cylinder inside a cylinder - moment of inertia
@NowIGetToLearnWhatAHeadIs since all we really need is the relationship between $d\theta$ and $d\phi$, consider that when $\theta$ increases by $d\theta$, the cylinder will have rotated by an arc length $R d\theta = a d\phi$.
Jun
24
revised Trying to derive compton scattering using 4-vectors
added 176 characters in body
Jun
24
comment Trying to derive compton scattering using 4-vectors
@iblue you're right, I updated my answer.
Jun
24
revised Trying to derive compton scattering using 4-vectors
deleted 380 characters in body
Jun
24
answered Trying to derive compton scattering using 4-vectors
Jun
20
awarded  Yearling
Feb
24
answered Moment of inertia for a triangle?
Feb
9
comment Lagrange's equation implying Newton's 2nd law?
@lionelbrits the potential for a charged particle in an electromagnetic field depends on velocity.
Feb
5
revised Trying to understand relativistic action of a massive point particle
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Feb
5
revised Trying to understand relativistic action of a massive point particle
added 278 characters in body
Feb
5
answered Trying to understand relativistic action of a massive point particle
Jan
20
answered Find the work done in moving an object along a vector r with a force F
Jan
20
answered Computing the angular momentum in spherical coordinates
Jan
16
revised Solving the Kepler problem
deleted 23 characters in body
Jan
16
revised Solving the Kepler problem
added 7 characters in body
Jan
16
answered Solving the Kepler problem