Question

A billiards ball of mass 0.4⁣kg strikes another, initially stationary ball of the same mass. The first ball is deflected and travels at an angle of 30∘ with its original direction. Its initial speed was 12⁣m/s and after the collision, it is 8m/s. What are the magnitude and direction of velocity of the second ball after collision?

Answer 1

conservation of momentum:
set up the equation in x,y directions, so you have two conservation of momentum equations. Notice two unknowns, direction and velocity of second ball. That should do it, two unknowns, two equations, and a bit of algebra (and basic trig). Here is a similar problem: https://www.jiskha.com/display.cgi?id=1391985689