power output

[mattskelley]

With your coffee cup engines how can you calculate the power output
(W) with only a thermometer

[Brent]

You can't use only a thermometer. In fact you don't even need a thermometer. Rig up a thread and a tiny weight to a pully and set the engine up so it raises a weight. Measure the time it takes to raise the weight. Look up the exact formula for measuring power this way in a physics book (I forgot it at the moment) make sure your units are correct and you'll get an accurate power output.

Brent Van Arsdell

[dirk.anteunis]

Using Brent's extremely simple and correct method:

w = d * m * 9.81 / t

where d = distance, expressed in metres that the weight was lifted; m = mass of the weight, expressed in kilogram; t = time it took to lift the weight, expressed in seconds; 9.81 = gravity constant, m/sec2

result w = result in Watt aka Joule/sec

I supposed that d is much smaller then the earth radius to simplify the formula

# dirk