So I have a piston connected to a flywheel. If i push the piston with a force F, how does the equation of motion look? I'm not confident about putting inertias into the same equation as accelerations? F = ma F = I(theta'') The force is changing with time. EDIT: So i have just realised that T = Ia, a is angular acceleration. So if i find resultant force of piston acting along line of tangential velocity on the flywheel, then moultiply it by r of the flywheel, Fr = Ia, then rearrange for a and i have angular acceleration of flywheel?