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"A ball with the mass of .440 kg moving east (+x direction) with a speed of 3.70 m/s collides head-on with a .220 kg ball at rest. If the collision is perfectly elastic, what will be the speed and direction of each object after the collision?

Relevant equations.

Conservation of momentum:

m* vi of b1 + m* vi of b2= m* vf of b1 + m* vi of b2

and conservation of kinetic energy...

1/2mvf^2= 1/2 mvi^2

Attempt at Solution:

.440(3.70) + .220(0)= .440(vf1) + .220(vf2)

1.63= .44(vf1) + .220(Vf2)

and then...

1/2 (.440)(3.7^2)= 1/2 (.440)(Vf^2) + 1/2(.220)(vf^2)

3.01= " "

**** Where do I go from here? Also, do I have to use the component form (as in, momentum of initial x component= momentum of final x component), etc? What about angles? I'm so confused because I feel like I should be using angles if its 2-D collisions, but none are given in the problem and I'm not sure if they'll go off a 90 degree angle or not?

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# Homework Help: 2-D Elastic Collision

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