Power question?

For a car to be driving at a constant velocity and not accelerate the drag force must equal the driving force. In the case it is 500 N plus the force due to gravity pulling the car down the hill. The force due to gravity pulling the car down the hill is:

mg.sin(a)

(710 x 9.81) x sin(2) = 243 N

So total resistive force = 743 N

Therefore the car is propelled up the hill with a force of 743 N.

Power is work done per second. We know that in one second the car travels 23 m, i.e. 23 m/s.

So, work done = force x distance;

work done = 23 * 743 = 17089 J

This is done over 1 second so:

Power = 17089 / 1 = 17089 W or 17 KW

the power required is equal to the force against which the engine is pushing times the velocity of the car.

we know the velocity (23 m/s)

we know the drag force ( 500 N)

we have to calculate the gravitational force that is trying to push the car backwards. using trigonometry, it is equal to

m*g*sin(2 degrees), where m=710 kg, and g = 9.8 m/s^2.

so the whole formula looks like:

23 * (500 + 710*9.8*sin(2 degrees))

when i plug this into my calculator i get about 17085 watts.