Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Maximum acceleration of a Porsche on a concrete surface?

  1. Aug 12, 2005 #1
    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
     
  2. jcsd
  3. Aug 12, 2005 #2

    Doc Al

    User Avatar

    Staff: Mentor

    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.
     
  4. Aug 12, 2005 #3
    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?
     
  5. Aug 12, 2005 #4

    Doc Al

    User Avatar

    Staff: Mentor

    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?
     
  6. Aug 12, 2005 #5
    ooo right so

    1*9.81*(2/3)m=m(total)*a ok that should workk thanks!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook