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: Understanding about momentum

  1. Nov 2, 2003 #1
    this problem needs alittle understanding about momentum, something i dont understand that much.

    A ball of mass 600g is moving 12 m/s[e]. The ball suddenly explodes into three equal mass pieces. One piece heads north at 6m/s, the second piece heads west at 5m/s. Determine the velocity of the third piece.

    Can someone plz show the calculations for me plz, thnx alot.
    Last edited by a moderator: Feb 7, 2013
  2. jcsd
  3. Nov 2, 2003 #2


    User Avatar
    Science Advisor

    Pretty straight forward. The initial velocity is <12, 0> (I'm taking my axes to point east and north). The intitial momentum vector is (mass times velocity) 0.6 KG <12 m/s, 0> = <7.2, 0>.

    After the "explosion", each piece has mass 200 mg= 0.2 kg. The piece heading north at 6 m/s has momentum .2<0, 6>= <0, 1.2>. The piece heading west at 5 m/s has momentum .2<-0.5, 0>= <-0.1, 0>.
    If we let <x, y> be the velocity of the third piece, its momentum is
    <.2x, .2y>.

    Conservation of momentum says: <7.2, 0>= <0- 0.1+ 0.2x, 1.2+ 0+ .2y> or 0.2x- .1= 7.2 and 0.2y+ 1.2= 0.
    Last edited by a moderator: Nov 3, 2003
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook