1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: Completely lost on this one

  1. Nov 25, 2009 #1
    1. The problem statement, all variables and given/known data
    A H2 was headed North and a convertible Mini Cooper was headed East. Due to faulty traffic signals, they collided, leaving a skid mark 7.6 m long at an angle of 51 degrees North of East. What was the initial velocity of each vehicle and, if the speed limit was 30 mph, who should get a ticket

    Using the above skid data, what would the intitial velocities and who should get the ticket if the East-bound car was a Smart Car and the North-bound car was the convertible Mini?

    Had to toss out the rest of the template as I really am in the dark. Seems really simple but I can't for the life of me recall how to attack this.
  2. jcsd
  3. Nov 26, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi 123bob123! :wink:

    (i assume the question gives you masses, and the coefficient of fricyion?)

    Momentum is always conserved in collisions, so use conservation of momentum (and find the final velocity from the stopping distance and the standard constant acceleration equations).

    What do you get? :smile:
  4. Nov 26, 2009 #3
    According to the problem itself, it doesn't give the mass for the vehicles or the coefficient which is what is throwing me for a loop. Is there any way to do this?
  5. Nov 26, 2009 #4
    mass of H2 > then mass of Mini coop

    assume same tires same road so friction coeff is the same
  6. Nov 26, 2009 #5
    Do you mind running me through the problem or a similar example? As I'm not entirely sure how I would be to make assumptions without the actual numbers.
  7. Nov 26, 2009 #6


    User Avatar
    Science Advisor
    Homework Helper

    Hi 123bob123! :smile:
    No. You need at least to know the coefficient of friction, and the approximate ratio of masses of the two vehicles. :frown:

    (do they expect you to look them up? :redface:)
  8. Nov 27, 2009 #7
    I really doubt that is the case. Must've been a mistake.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook