# Motor efficiency

1. May 5, 2006

### TSN79

In an assigment I'm using the general formula P=F*v, where P is the effect of a motor. The motor drives something through a series of sprockets, who's efficiency is 85 %, and so it seems intuitive to me to multiply the resulting P with 0,85 to get true effect, but apparently the solution divides by 0,85 which results in a higher P than to begin with. I don't get the logic in this, so if someone can explain why this is correct I would like to hear it.

2. May 7, 2006

### Päällikkö

What's the question?
Could it be that you're given the final output power (that is, after the sprockets), and asked the power of the motor?