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I have a system where I am trying to find the power generated by a DC electric generator. However, I am not very familiar with generators, so I am having difficulty determining the rotational velocity. I have the equation:

torque = Power/2pi * n, where n = revolutions per second.

For convenience, let us say that the torque = 10Nm. I want to find the power, but how can I do that when I do not not how quickly the generator is spinning? Obviously I am missing something, but I'm not sure what it is. Thanks!

Edit: to be a little more specific, given power = 2pi x 1m x 10M x n, where n, I assume, is the number of revolutions per second, can I find the wattage as a real number, not just a symbol?

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  • $\begingroup$ You can't calculate power output without the missing information. $\endgroup$ – David White Dec 31 '18 at 21:28
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Power is work done per second. Work is force times distance (if the force vector anf the distance vectors are parallel). Torque of 10Nm means that at a radius of 1 meter the device can exert a force (in the direction of turn) of 10N. It can exert that force in a direction parallel to the tangent to a 1m radius circle around the shaft, so over a distance of 2pi x radius, doing work of 2pi x 1m x 10N per revolution. The power, then, is 2pi x 1m x 10M x n.

Usually a generator receives torque rather than producing torque. A motor produces torque.

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  • $\begingroup$ Thanks! So, to be a little more specific, given power = 2pi x 1m x 10M x n, where n, I assume, is the number of revolutions per second, can I find the wattage as a real number, not just a symbol? $\endgroup$ – Jmeeks29ig Dec 31 '18 at 21:53
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    $\begingroup$ Sure. 1 watt = 1 Newton-meter per second. If you do the multiplication I gave you, the result is in watts. $\endgroup$ – S. McGrew Dec 31 '18 at 23:07

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