Homework Help: Help! elastic head-on collision

1. Dec 7, 2005

snowbelle

a 3.42g object moving to the right at 16.4 cm/s makes an elastic head-on collision with a 6.84g object that is initially at rest. find the velocity of the first object immediately after collision. Answer in units of cm/s. What fraction of the initial kinetic energy is transferred to the 6.84g object?

I dont understand how to do this problem. I think for the first part is it
M1v1i+M2V2i=M1V1f+M2V2f
and im lost after that. I completely dont get part 2

2. Dec 7, 2005

NateTG

Indeed, you have:
[tex]P_{\rm{initial}}=P_{\rm{final}}[/itex]
which gives you one equation.

But, you have two unknowns ($v_1$ and $v_2$), so you'll need another equation. What do you know about elastic collisions?

3. Dec 7, 2005

snowbelle

energy and momentum is conserved in elastic collisions?

4. Dec 7, 2005

NateTG

Right. The equation you have listed only deals with momentum.

5. Dec 7, 2005

snowbelle

hmm i still dont get it

6. Dec 7, 2005

NateTG

Can you write expressions for the total kinetic energy before and after the collision?