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: 2D - Momentum Question, Grade 12 Canadian Physics

  1. Nov 5, 2011 #1
    1. The problem statement, all variables and given/known data
    2 cars collide at an intersection.
    one car which has a mass of 1,400kg has a velocity of 45 km/h;
    the other car has a mass of 1,300kg and has a velocity of 39 km/h[E]
    The cars has an inelastic collision. What are their velocity after the collision

    2. Relevant equations

    Conservation of momentum: P total = P total prime

    3. The attempt at a solution

    I have tried on numerous occasions but have not achieved the correct answer.

    The correct answer should be: "30 km/h [ 51 South of East.]

    I got the correct magnitude of the velocity which is 30 km/h. Easy enough, but i didn't get the degrees required. Additional vector diagram is appreciated.
  2. jcsd
  3. Nov 5, 2011 #2
    Try to draw the vector diagram for the initial total momentum of the system.
  4. Nov 5, 2011 #3
    @grzz I figured out what i did wrong. When i calculated for the theta of the vector triangle. I simply used the velocities. Instead i tried it with m(v) and it worked for me. Thanks.
  5. Nov 5, 2011 #4
    You just confirmed that it is the total momentum that is conserved and not the total velocity!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook