# Q & A: power

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Q:
Hello, power=Fv where F is force and v is velocity. what if the object accelerates and there is a range of velocities...which v do we take? or do we take the average velocity (u+v)/2 so that power=F(u+v)/2 ??
- Anonymous (age 15)
A:
Power mean the rate at which work is being done at some particular time. So the power at that time depends only on F and v at that time.

Now if you want the average power over some period, it depends on what's changing. If F is fixed, then of course v changes. But for fixed F the average Fv is just Fvave, as you suggested.  If both F and v are changing, there's generally no shortcut to avoid actually averaging Fv.

Mike W.

(published on 01/08/11)