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Homework Help: Particle collision

  1. Aug 26, 2015 #1
    A particle of mass 2kg moving with speed 6m/s collides ellastically with another particle of mass 4kg travelling in same direction with a speed of 2m/s. Find max deflection of 2kg particle?
    Last edited by a moderator: Aug 28, 2015
  2. jcsd
  3. Aug 26, 2015 #2


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    Gold Member

    Hi lawrence1234. Welcome to the forum.

    For homework help you need to put this into the template. Also, you need to show that you have made some effort to solve your own problem. People here are not supposed to just do your homework for you. But I will give you some hints.

    Problems of this nature are usually easier to solve if you look at the collision in the centre of momentum frame. In that frame the two particles will have equal but opposite momentum. In that frame an elastic collision is very simple. The particles come in with the same-but-opposite-sign momentum. They go out with same-but-opposite-sign momentum but in some other direction. But in this problem you don't know the angle they go out at. So you include this angle as a variable.

    Then you transform the after-collision situation back to the lab frame and work out the possible angles the 2 kg particle could take. And find the maximum deflection.
  4. Aug 27, 2015 #3
  5. Aug 27, 2015 #4
    yeah srry i
  6. Aug 28, 2015 #5
    im getting 4 variables here and 4 equations here by conserviing momentum and energy in x and y direction
    is there any other easier way to solve it
    becoz its a multiple choice single correct answer it should not be that lenghty
  7. Aug 28, 2015 #6
    yeah and this was not homework srry i just had a doubt from my cource book
  8. Aug 28, 2015 #7


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    Did you do it the way I said? If you do then you don't get four variables, you get one. The angle will be the only variable left over.

    If you want more help, please show your work.
  9. Aug 28, 2015 #8
    k ill try it again
  10. Aug 28, 2015 #9


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    Staff: Mentor

    We treat all schoolwork-type questions as homework here. Next time you start a schoolwork thread, use the Homework Help Template and fill out the sections on the Relevant Equations and show your Attempt at a Solution. That's in the PF rules (see Info at the top of the page).
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