Question

A 10kg ball with a velocity of 10m/s collides head on in an elastic manner with a 5kg ball at rest. What are the velocities after the collision?

Answer 1

momentum is conserved:

10*10 +5*0=10V1 + 5V2 (the velocities after collision
V1=(10-.5 V2)
conservation of energy
1/2 * 10*10^2=1/2*10*V1^2 + 1/2*5*V2^2 now substiture..
500=5((10-.5 V2)^2) + 2.5 V2^2
200=2(100-100V2 + 25V2^2) + 2.5 V2^2 collect terms, solve the quadratic.