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: Inelastic collisions?

  1. Aug 9, 2007 #1
    Putty of mass 5 is compresses a spring with stiffness consonant 3. The spring is stretched and the putty has a completely inelastic collision with another putty of mass 15. How fast and how far do the putties travel?

    I have no idea how to begin.

  2. jcsd
  3. Aug 9, 2007 #2
    me neither...
    are you sure it didn't tell you the displacement of the spring, if it gave you that the problem would be solvable
  4. Aug 9, 2007 #3
    oh, right sorry. i forgot to include that -- 'with a distance of 6'

    thanks for pointing that out.
  5. Aug 9, 2007 #4
    oh, in that case...
    PE=1/2kx^2 for spring.... where k is the stiffness constant and x is the displacement
    the spring transfers all its PE to the first putty's KE, so now you want to do KE=1/2mv^2 solving for the velocity of the first putty after it leaves the spring...
    then do conservation of momentum.... mv before= mv after
    *the mass and velocity before is just the mass and velocity of the first putty, the mass after is the mass of both together and the velocity after is the joint velocity which you are solving for...
    uhhh, the distance im not so sure about
    you didn't mention any friction in the problem so I assumed there was none... what exactly makes them slow down?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook