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Homework Help: Head-on collisions

  1. Oct 23, 2009 #1
    1. A car (mass = 1060 kg) is traveling at 43 m/s when it collides head-on with a sport utility vehicle (mass = 2550 kg) traveling in the opposite direction. In the collision, the two vehicles come to a halt. At what speed was the sport utility vehicle traveling?

    2. COLM states: m1Vf1 + m2Vf2 = m1Vi1 + m2Vi2

    3. Since we know the masses of the two vehicles and the initial velocity of the first car, and since the final velocities of both are zero, I plugged in the values for the variables and got the equation 0= (1060 kg)(43 m/s) + (2550 kg)(Vi2)

    I did the math and got that Vi2= (1060 kg * 43 m/s)/(2550 kg) but the answer I got here, -20.26 m/s, is apparently wrong. Can someone tell me where I went wrong?
  2. jcsd
  3. Oct 23, 2009 #2


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    Homework Helper

    your answer is 20.26 m/s in the opposite direction


    -20.26 m/s in the opposite direction
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