- 517

- 31

- Problem Statement
- See image

- Relevant Equations
- L=T-V, ke=1/2mv^2

I think my confusion on this is where the best origin for polar coordinates is. I've tried the center of the circle, and note the triangle made from the r coordinate reaching out to ##m, a,## and ##l+a\theta##. Then

$$r=\sqrt{a^2+(l+a\theta)^2}$$

$$\dot r = \frac {a(l+a\theta)} {\sqrt{a^2+(l+a\theta)^2}}$$

but my book has a much simpler expression for T where ##\dot r = 0##...I am missing some crucial insight.