- #1

WrongMan

- 149

- 15

## Homework Statement

So this is just something i came up with to check if i am understanding everything allright, it all comes down to collisions in regard to the center of mass

So two "masses" experience a glancing collision

M1:

vi - 3m/s (refered to as v1i) ;

m - 2Kg (m1)

M2

vi - 0 (v2i) ;

m - 6Kg (m2)

## Homework Equations

what i did was figure out the speed of the center of mass (Vcm) using:

Eq(1) (v1i*m1 +v2i*m2)/(m1+m2)

and then since the Vcm is constant before and after the collision (right?) i figured out v1f and v2f because:

eq(2) v2f=2vcm-v2i (and same for v1f)

this is were i get stuck, using the system:

Sys(1)

-v1f*m1*sin(theta) + v2f*m2*sin(theta2)=0

m1*v1i=v1f*m1*cosin(theta) + v2f*m2*cosin(theta2)

## The Attempt at a Solution

so using eq 1 and 2 i get Vcm=3/4 and v1f=-3/2 and v2f=3/2

and i can't solve the system, all the other glancing colision problems i have seen give one of the angles.

plus the masses are different so the angle bettwen theta and theta2 isn't 90º, i don't know what to do.

I am probably doing something wrong as everything i have seen says i can't solve this kind of problem if i am not given one of the 4 unknown quantities (the two angles and the two final velocities) so probably my mistake is regarding the two final velocities, i don't know.