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Homework Help: Use of equation of motion

  1. Oct 21, 2012 #1
    1. The problem statement, all variables and given/known data
    Two cars, both of mass m, collide and stick together. Prior to the collision, one car had been traveling north at speed 2v, while the second was traveling at speed v at an angle phi south of east. After the collision, the two-car system travels at speed v_final at an angle theta east of north

    Find the speed v_final of the joined cars after the collision.
    Express your answer in terms of v and phi.

    2. Relevant equations
    i am dividing the velocity into components using x-component and y-components of v.
    vx = vcosθ
    vy = vsinθ
    then finding the magnitude, v = (vx^2 + vy^2)^1/2
    3. The attempt at a solution

    ok so my two equations are
    vx = vcos and vy = 2v - vsin

    after trying to find the magnitude i found the answer v(5-4sinθ)^1/2 but it says the answer is not right.
    i am using θ instead of phi

    Attached Files:

    Last edited: Oct 21, 2012
  2. jcsd
  3. Oct 21, 2012 #2
    There is no question in the problem statement. What do you need to find? This smells like an inelastic collision scenario requiring use of the principle of conservation of linear momentum.
  4. Oct 21, 2012 #3
    oh sorry..i have edited it
  5. Oct 21, 2012 #4
    Yeah, use conservation of linear momentum as it relates to collisions. Should be in your book.
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