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Homework Help: Kinetic Energy and a Collision

  1. Aug 15, 2010 #1
    1. The problem statement, all variables and given/known data
    A 8.5 kg steel ball, travelling left to right at 12 m/s, undergoes an elastic collision with a 5 kg steel ball at rest. To the nearest Joule, what is the Total Kinetic Energy of the two balls after collision? If the first ball has a mass of 10 kg and the second ball is travelling at it with a speed of 3 m/s, what is the velocity, to one decimal place, of the first ball after collision? What is the velocity of the second ball to one decimal place?

    2. Relevant equations


    3. The attempt at a solution
    Question 1:
    1/2 (8.5)(122)= 612 J
    Question 2 & 3:
    I'm not sure the equation needed to solve for the needed. I'm pretty sure that if I can get question 2 then the same method will be used to solve question 3.
  2. jcsd
  3. Aug 16, 2010 #2


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    For questions 2 and 3 you need to conserve momentum in addition to energy conservation.
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