- #1
dotmatrix
- 15
- 0
Homework Statement
Hey guys, not much of a physicist. But, I am fairly certain I am right.
We are using a "prony brake" at school to calculate torque in a motor. To me the amount of force supplied should equal the amount of force the motor can turn ie: when the motor stops the force applied on the "prony brake" is 33 oz.
Now my instructor has given us an equation that says that the radius of the shaft of the motor has something to do with the calculation of the force applied.
My problem is a) we did not apply the force to the shaft but instead a coupler which was roughly 4" in diameter (as opposed to a one inch shaft)
b) the force applied was by a belt which squeezed half of the circumference of the shaft
c) it varied with friction (we poured water on the belt to keep it cool and it reduced the amount of "force"}
So I know enough to say that the equation isn't quite right. And I would like to say that the force that I am exerting on the motor is equivalent to the torque (as it is a frictional force that opposes the rotation) but I don't actually know anything for sure. I think that it shouldn't have anything to do with mass times the radius of the shaft or whatever.