1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Provincial Exam: Simple momentum explosion question

  1. Jan 21, 2010 #1
    1. The problem statement, all variables and given/known data

    A 1.0kg physics puck is at rest when a small explosion breaks it into three pieces. A 0.50 kg piece, goes north at 10 m/s, a .3 kg piece goes east at 20 m/s. What is the magnitude of the momentum of the third piece.

    2. Relevant equations

    [tex]p = mv[/tex]
    Momentum Before = Momentum After

    3. The attempt at a solution

    So i know that the momentum before is zero, so the sum of the momentum on the x axis is zero, and the sum on the y axis is zero.

    Because the first two pieces are at right angles to eachother, i calculated the net momentum, or their resultant, and stated that the momentum of the third piece should be equal and opposite to maintain the law of momentum conservation.

    So i determined: the first piece had a momentum of 5 kg m/s north, the second, 6 kg m/s east.

    Plugged the values into the pythagorean theorum and got 7.8 kg m/s..

    Which is an answer on the sheet, but it's wrong. The correct answer is 3.3 kg m/s

    Could anyone tell me where i went wrong??

  2. jcsd
  3. Jan 21, 2010 #2
    *bump* :(
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook