# Homework Help: Noncentral Elastic Collision

1. Feb 8, 2010

### EPhoenix

1. The problem statement, all variables and given/known data

First sphere m=0.3 kg collide noncentraly and elasticaly with other sphere of m= 0.35 kg and transfer 79% of first sphere kinetic energy during that collision... u1 is not defined, u2 = 0 m/s

Ratio between speed after collision v1 : v2 = ??

2. Relevant equations

m1u1 + m2u2 = m1v1 + m2v2

3. The attempt at a solution

Tryied to make Ek = Ek1 + Ek2

m1u1 = m1v1 + m2v2

m2v2 = 0.79 m1u1
v2 = 0.677 u1

m1v1 = 0.21 m1u1

v1= 0.21 u1

so ratio would be

v1 : v2 = 0.21u1 : 0.677u1

so in conclusion

v1 : v2 = 1 : 3.224

But I don't know if it's false or right...

Last edited: Feb 8, 2010
2. Feb 8, 2010

### thebigstar25

hmmm , your solution doesnt seem logical enough to me .. for example why didnt you use the fact that k=0.mv^2 (or p^2/2m) ??notice what is the relationship between the kinetic energy and the velocity(or momentum) .. how would that change your calculations? .. please try again ..

3. Feb 8, 2010

### EPhoenix

Yeah... I got right solution after applying it with kinetic formula...

Thx nevertheless :)