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Jared94

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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.