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: 2D Collision using momentum

  1. Nov 19, 2015 #1
    1. The problem statement, all variables and given/known data
    Two equal mass hockey pucks undergo a glancing collision. Puck 1 is initially at rest and is struck by puck 2 travelling at a velocity of 13 m/s[E]. Puck 1 travels at an angle of [E18N] after the collision. Puck 2 travels at an angle of [E4S]. Determine the final velocity of each puck.

    How do I solve the problem using conservation of momentum since I only have the two initial velocities?

    2. Relevant equations
    mv1+mv2 = mv1f+mv2f

    3. The attempt at a solution
    I've tried to use the equations for a perfectly elastic collision
    Last edited: Nov 19, 2015
  2. jcsd
  3. Nov 19, 2015 #2
    If they have equal masses, shouldn't puck 2 have a velocity of 0 and not move in any direction? I'm not sure but that is how I learned the conservation of momentum.
  4. Nov 19, 2015 #3
    Well puck 1 has a velocity of zero and puck 2 strikes it, so in the conservation of momentum equation, v1 cancels out along with all the masses. The equation then becomes v2 = v1f + v2f. With that equation there's two unknown values and one known, so I'm not sure how to solve it from this point on.
  5. Nov 19, 2015 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    That's only if it's a head-on elastic collision. This is a glancing collision.
  6. Nov 19, 2015 #5

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    What does angle [E18N] mean? Is it 18 degrees north of east? Is is 18 degrees east of north? Is it something else?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted