# P=Fv what force represents

1. Jul 1, 2008

### nokia8650

In the equation P=Fv, I am unsure of what exactly the force reprents. Let's say that there is a car of mass 1000kg travelling at a constant velocity 30m/s, driven by an engine developing 25kW. Since F=P/v, F= 833.33N. However, this is clearly not the resultant force on the car - since the resultant force is 0N. Does this mean that resistive forces must be 833.33N? If so, please can someone explain why a force is needed for this motion? Also, if the power were to be increased, would the force increase, or the velocity increase?

Thanks

2. Jul 1, 2008

### Dick

Re: P=Fv

You've already explained it. You've computed the force that the engine is applying to the car to overcome the friction force. So, yes, the friction force is 833.33N.