# Dynamics: conversvation of angular momentum (concept question)

1. Jan 9, 2010

### silentwf

1. The problem statement, all variables and given/known data
This is more of a concept problem rather than solving it. So the questions are as below and the solution provided by the book. (sorry about the large sizes)

http://img190.imageshack.us/img190/6366/201019dynamics.png [Broken]
http://img130.imageshack.us/img130/5720/201019dynamics2.png [Broken]
Both of the questions involve one person jumping off an object (whether rotating or not). My question is, in both solutions, the book provides that the person jumping off will have an extra angular velocity other than his/her own, why?
Like in the first picture, the solution uses
$-m_{m}(v-\omegaa)a+m_{p}(\frac{c^{2}}{12}+b^{2})\omega$
Why an extra $\omega$ (velocity) for the man? Why not just v?

And in the second picture where $M_{1}(v+\omega_{3}a)a$, again, why an extra $\omega$ (or velocity)

(for question 2 (with the kids), its just the second part (part b), the extra $\omega_{2}$ i already solved)
2. Relevant equations
$\Sigma H_{0} = \Sigma H_{1}$

3. The attempt at a solution
(my equations are pretty much equivalent as those provided in the picture, except the part i dont get)

Last edited by a moderator: May 4, 2017