Energy Conservation: Velocity of Marbles 1, 2 and 3

[xshezsciencex]

Three marbles have the same mass. Two of them touch each other and are aligned perpendicular to the path of marble 1. The velocity of marble 1 has magnitude v (initial)=10m/s and is directed at the contact point of marbles 2 and 3.

After the elastic collision what are the speed and direction of the velocity of all marble 1, 2 and 3?

my attempt:
v(initial)m = 2mv(subscript2) costheta + v(final)m
v(initial)^2 m= v(final)^2m/2 + 2vthetha^2*20m/2

theta= v(subscript2)sintheta-v(subscript3)sintheta

 

[tiny-tim]

Hi xshezsciencex!

This is very confusing.

Can you please write it out again, clearly, using the X² and X₂ tags just above the Reply box, and using "i" and "f" for "intial" and "final" (this is normal practice), and this theta: θ.