Calculating Change in Kinetic Energy for 1D Collision

[dbb2112]

Homework Statement

A 2kg object moving 5m/s in the positive x direction has a one dimensional elastic collision with a 4kg object moving at 1m/s in the same direction. What is the resulting change in kinetic energy of the 4 kg object?

Homework Equations

K=1/2 m*v^2 m1v1+m2v2=(m1+m2)V

The Attempt at a Solution

after solving for V would i just plug that into the kinetic energy and subtract it from the original kinetic energy of the 4kg object?

 

[Nissen, Søren Rune]

If you find V correctly then yes, you can just find the new kinetic energy of the 4 kg object and calculate the difference.'

EDIT: Although I wouldn't trust your stated equation for finding the new velocity. If you look at your original post, the words "elastic collision" have been underlined. Try following that link, it should have the relevant equation.

 

[dbb2112]

o wow i read that wrong.

 

[dbb2112]

so i would use m1v1+M2V2=M1V1'+M2V2' but i do not know either of the final velocities?

 

[Nissen, Søren Rune]

OK, I need to know: Your thread title says "inelastic collision" but your 1st post says "elastic collision." Which is it?