Hi there, really trying to grasp these concepts for one of my engineering papers. This is basic stuff I realised now that I never really understood. If I've got two shafts, two wheels per shaft meaning four wheels in total, each wheel is 60 mm in diameter, and the power consumed by the system in providing a constant horizontal velocity of 0.15 m/s is 200W, what is the torque in each wheel? The wheels are rubber coated, and the wheels are acting upon a steel surface (take coefficient of friction to be 0.7). This is how I've tried solved the problem: Power = Torque x angular velocity w = v / r = 0.15 / 0.030 = 5 rad/s Torque = P / w = 200 / 5 = 40 Nm Now here's where I get stuck; the concept of what I've calculated: Now since there are 4 wheels (instead of just 1 wheel) AND two shafts (two wheels in each shaft), how do I interpret this torque of 40 Nm? Is the force per wheel just force = Power / velocity or is this force divided amongst the 4 wheels? With the friction, since the system is moving at a constant speed of 0.15 m/s, will the thrust force equal the frictional forces? The force here doesn't equal the force calculated via the torque of 40 Nm, is this because of a transmission efficiency? So to summarise: If power consumed in moving all four wheels at a constant speed is 200W, is the torque of 40 Nm I calculated split between the four wheels equally? Power = force x velocity, calculating the force from here doesn't equal the total frictional forces etc. etc. Thanks in advance.