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: Average Power delivered to Engine

  1. Dec 19, 2006 #1
    1. The problem statement, all variables and given/known data
    A 1000 kg car, starting from rest, accelerates uniformly to 15 m/s in ten seconds. Assume air resistance is constant at 300N. What is the average power delivered by the engine?

    a. 13500 W
    b.18000 W
    c. 23000 W
    d. 27000 W

    2. Relevant equations
    Average power = work/time
    work = force(x) where x is magnitude of displacement.
    force= mass x acceleration

    3. The attempt at a solution

    the force is equal to 1000 kg x 15 m/s = 15000

    I don't know how to factor in air resistance, or arrive at a final answer. The answer is A...
  2. jcsd
  3. Dec 19, 2006 #2
    explain how you got the force of the car again...
  4. Dec 19, 2006 #3
    force = mass times acceleration
    1000 x 15= 15000
  5. Dec 19, 2006 #4
    what is the units of the 15 value though
  6. Dec 19, 2006 #5
    ok.... i think i got it.... after getting the correct force (and units) times the displacement of x, (1800 * 75)/10.... gives the correct answer.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook