Elastic Collision between 2 Particles

[Kyliticus]

Hi, here's my problem.

A particle of m1 and initial speed v0 strikes a stationary particle of mass m2, and scatters at 30 degrees to its original direction with speed v0/3. Find the angle, in degrees, between the directions of the two particles after the collision.

I found that the velocity of the m2 after the collision to be 2/3v0 due to conservation of energy.

Can anyone give me ideas on how to find the contained angle? Thank you.

 

[rock.freak667]

Since it is a collision as well, you'd need to apply conservation of linear momentum in both the x and y directions.