watts

philo51

A Porsche 944 Turbo has a rated power of 217 hp and a mass, with the driver, of 1460 kg. Two-thirds of the car's weight is over the drive wheels.

What is the maximum acceleration of the Porsche on a concrete surface where static friction=1.0

1hp=476watts
217hp=103292 watts

and power= Force*velo but whats the force?

What is the speed of the Porsche at maximum power output
thats easy if i get the force i just solve for v

If the Porsche accelerates at , how long does it take until it reaches the maximum power output?
again easy if i can get the first part. any help is appreciated

Doc Al

The force acting on the car is the static friction of the road on the tires. The maximum possible static friction force is given by [itex]\mu N[/itex], where N is the normal force pressing the surfaces together. That should get you going.

philo51

yea i think i got that but im not sure if the rest is right then

u*N=ma

(1.0*1460kg*9.81)/1460 = a? that doesnt seem right is there another force?

Doc Al

Friction is the only horizontal force you need worry about. (I presume you may ignore air resistance.) But note that you were told "Two-thirds of the car's weight is over the drive wheels". How would that modify the normal force used to calculate the friction?

philo51

ooo right so

1*9.81*(2/3)m=m(total)*a ok that should workk thanks!