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

Deriving distance traveled

  1. Nov 23, 2011 #1
    A car can accelerate 0-60 mph in 8.6 seconds and 0-100 mph in 26.1 seconds. How far (in feet) would the car have to travel in order to accelerate from 0-81 mph?
  2. jcsd
  3. Nov 23, 2011 #2
    The acceleration rate from 0-60 mph is different than the acceleration rate from 0-100 mph. You could assume that the rate of acceleration is inversely proportional to the final speed (linear), but that really isn't the case with cars. So, with the given data, this problem is not solvable. The best you can do is find an estimate.
  4. Nov 23, 2011 #3


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    When I was first presented with the "Equations of Motion" I clearly hadn't been listening to 'Sir' well enough and I got very cross about just this point. I just thought ":How could you possibly tell?".
    It took some time to take on board the qualification 'uniform acceleration'.
  5. Nov 23, 2011 #4
    What would the estimate be then?
  6. Nov 23, 2011 #5
    Averaging the acceleration yields a result of 271.37m to reach the 81mph (36.21m/s).
    It is a rough estimation, given that it should take more time to get that extra 19 mph from 81 to 100 mph than the 21 mph from 60 to 81 mph. Aerodynamic drag is proportional to the speed squared.
  7. Nov 23, 2011 #6
    271.37 m = 890.3 ft
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook