Solving Three Ball Collision: Elastic Collision with M and m Masses

[momo1111]

Homework Statement

Ball of mass M collide two balls of mass m , elastic collision .
initially, M has velocity v , and two balls are stationary.
after the collision the two masses move ,like in figure , v_a , v_b /
What is the velocity V ,of mass M after the collision ?

Homework Equations

The Attempt at a Solution

try to manipulate the equations , with no success.
help

 

[Dr. Courtney]

Your notation is a bit confusing, but I think I get it.

Consider that you have four scalar unknowns (vx, vy, v1, and v2) but only three equations.

 

[momo1111]

fix notation

 

[haruspex]

Consider that you have four scalar unknowns (vx, vy, v1, and v2) but only three equations.

The way I read it, v_A, v_B are given, so it's 3 equations and 2 unknowns. Still not good. Could choose to ignore the elasticity condition.

momo, are you sure you have quoted the question exactly?
I assume your last equation in post #3 should read v'²=v'_x²+v'_y².