A ball of mass m makes a head-on elastic collision with a second ball (at rest) and rebounds with a speed equal to one-third its original speed. What is the mass of the second ball?

Answer 1

7-9

Answer 2

0.5m

Answer 3

Since the collision is elastic then kinetic energy will be constant......1/2m1v1^2=1/2m1v1^2+1/m2v2^2.....
Given m1=m
By combining the equations and making v1 the subject
V1=[{v1(m1-m2)}+(2m2*v2)]/(m1+m2)

Note:v2=0 after computing..the mass of the second ball is 1/2m