**1. The problem statement, all variables and given/known data**

can someone explain why angular momentum is conserved about O and how they got that statement for the conservation of angular momentum about O

**2. Relevant equations**

M(P) = d/dt (h(P)) + v(P) x mv(G)

h(P) = I(G)w + r(G/P) x mv(G)

**3. The attempt at a solution**

http://ift.tt/1hJUlIw