Work done and power

[Guest daze]

The road wheels of a car exert a tractive effort of 1000N when travelling at 50KM/h.

Calculate the work done per minute?express in Joules

What power is the power developed by the car at this speed? express your answer in kilowatts.

Can anybody help with how to work this out?

cheers

[5614]

Work done = energy transferred = force x distance moved in direction of force

(so how long was the car moving for?)

 

power = energy transferred / time

 

Again, it's just a case of knowing the formulae.

 

Power is energy per unit of time.

[swansont]

Or, if you want to skip a step, since (integral) dW= (integral) F dx, if you take the derivative with respect to time, you get

 

(integral) dW/dt = Power = (integral) F dx/dt, but dx/dt is v, so as long as F is constant, P = Fv (technically there's a dot product there, so in scalar form they have to be in the same direction, or you use Fv cos(theta) )