1. The problem statement, all variables and given/known data A girl of mass 28.1 kg stands on the rim of a frictionless merry-go-round of radius 1.58 m and rotational inertia 433 kg·m2 that is not moving. She throws a rock of mass 670 g horizontally in a direction that is tangent to the outer edge of the merry-go-round. The speed of the rock, relative to the ground, is 7.78 m/s. Afterward, what are (a) the angular speed of the merry-go-round and (b) the linear speed of the girl? 2. Relevant equations Mass M = 28.1 kg radius r = 1.58 m R-Inertia = 433 Kg.m2 mass of rock = 670g = .67 kg (tangent to merry-go-round) speed of rock = 7.78 m.s now is the angular speed ω of merry-go-round = ? we know ω = L/Inertia or (m.r.v)/inertia. Now what is velocity of the system? is it 7.78? 3. The attempt at a solution if yes then ω = [(28.1+.67)*1.58*7.78)]/433 ≈ 0.81674 rad/sec is linear speed of the girl = 0.816748*r v = ω/r ??