1. The problem statement, all variables and given/known data Gear wheels B and D are mounted on a right-angled carrier, C. They mesh with a fixed gear wheel A, of radius 200mm. Each of the small wheels has a mass of 3kg and a radius of 100mm and may be considered to be a uniform circular disc. The carrier, which is freely pivoted about O, has a total mass of 6kg and may be considered as two uniform rods, each of legnth, 300mm. The assembly is released from rest with the centre of B vertically above O. Find the angular velocity of the small wheels when the centre of D just reaches the point vertically below O. http://twitpic.com/mpa24 2. Relevant equations Rotational and Translation Impulse-Momentum Equations 3. The attempt at a solution I'm just starting to attempt this question by looking at the bars separately. In the case of bar BC, Im not quite sure what force are acting on the bar apart from its weight. Is there a force exerted by the gear B? This leads me to wonder what to put in the equation: work done=change in ke for the rotational component. I know the right hand side would be 1/2 I(Theta dot2^2 - 0) Please help!