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Homework Help: Collisions problem completed - is it correct?

  1. Sep 19, 2010 #1
    Hello - I am pretty sure this is correct but there is no answer for me to check. My friend (who is a lot smarter than me :P ) got a different answer entirely. Is the following answers correct?

    1. The problem statement, all variables and given/known data
    Puck A has a mass of 0.0300 kg and is moving along the x axis with a velocity of +4.20 m/s. It makes a collision with puck B, which has a mass of 0.0600 kg and is initially at rest. The collision is not head-on. After the collision, the two pucks fly apart with the angles shown in the drawing. Find the speed of (a) puck A and (b) puck B.

    puck a is 65 degrees above x axis
    puck b is 37 degrees below the x axis

    3. The attempt at a solution

    (0.0300) (4.2) + 0 = (0.0300) (VA COS 65) + .0600 (VB COS 37)
    0.126 = 0.0127 VA + 0.0479VB

    0 = 0.0300 (VA SIN 65) + (0.0600)(-VBSIN 37)
    = 0.0272 VA + -0.0361 VB
    0.0361VB = 0.0272VA
    VB = 0.0272VA/0.0361
    VB = 0.753 VA

    0.126 = 0.0127 VA + 0.0479VB
    0.126 = 0.0127 VA + (0.0479)(0.753)
    0.126 = 0.0127 VA + 0.0361 VA
    0.126 = 0.0488 VA
    VA = 0.126/10.0488
    VA = 2.58 m/s

    VB = 2.58 m/s x 0.753
    = 1.94m/s
     
    Last edited: Sep 19, 2010
  2. jcsd
  3. Sep 19, 2010 #2

    rl.bhat

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    Homework Helper

    Your answer appears to be correct.
     
  4. Sep 19, 2010 #3
    Thank you very much - I appreciate it.
     
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