# Calculating power from torque

so for my project im designing a Tesla turbine and have calculated that the torque it will output is 38Nm. I would like to know what more information I would need that i could calculate theoretically to calculate how much power it would output from this.

Thanks.

• This is a really basic physics question. Dec 28, 2016 at 12:55
• Power = torque * rotational speed. If using SI units, that's Nm * radians/second, giving watts. Dec 28, 2016 at 13:31

general power formula is 2*3.14159 * N *T

you need to know revolutions per second for finding power. there are various tachometers available. (stroboscope,aluminum cup,mechanical tachometer, etc) get the reading of revolution per min. convert it to rev per sec.

then use it in the formula p = 2*3.1415*N*(38)

• there is even a mobile app that can estimate revolutions per minute Dec 28, 2016 at 13:01
• The 2*Pi is only an artefact of not using SI units properly. Dec 28, 2016 at 13:33
• gee, if you convert rpm to rad/s shouldnt there be a 60 in there someplace? Dec 28, 2016 at 13:57
• If you are using rad/sec, then you don't need to divide by 60. Power is in joule per second Dec 28, 2016 at 14:33

Power is force times speed.

If your shaft is turning at 1 Hz, for example, then the power is

(38 N)(2Π m/s) = 239 Nm/s = 239 W