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: Poorly worded question

  1. Nov 1, 2004 #1
    ok here is the question exaclty- its worth 5 marks so i dont know what im missing..

    A car with a mass of 850kg is moving in a straight line at a constant speed of 110km/h. It is brought to rest in 10.0s. What constant force is acting to stop the car?
  2. jcsd
  3. Nov 1, 2004 #2
    [tex]F_{avg}\Delta t = m\delta v[/tex]
  4. Nov 1, 2004 #3
    Looks like an impulse question.
  5. Nov 1, 2004 #4
    Thanks anyways guys but i got it. I think i was thinking it was asking what force as in friction or wind etc. was stopping it but its asking the force it would take to stop it in that time.
  6. Nov 1, 2004 #5

    Doc Al

    User Avatar

    Staff: Mentor

    If you are not familiar with impulse/momentum, you can always use kinematics to find the acceleration, then apply Newton's 2nd law to find the force.
  7. Nov 2, 2004 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Good point...I guess they should have said "determine the magnitude of the constant force that brings the car to a stop".
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook