A ball of mass 3m collides head-on with a initially stationary ball of mass m. No kinetic energy is transformed into heat, or sound. In what direction is the mass-3m ball moving after the collision, and how fast is it going compared to its original velocity?
The Attempt at a Solution
I initially set it up as p1i +p2i = p1f +p2f
p2i being zero it was discarded from the equation
so p1i = p1f + p2f
3mv = 3mv1f + mv2f since m is a unknown constant I can remove it from the equation
3v = 3v1f + v2f
unfortunately, this is where I am stuck :(
or should I have calculated this via Kinetic energy?