A ball of mass m makes a head-on elastic collision with a second ball (at rest) and rebounds with a speed equal to 0.300 its original speed. What is the mass of the second ball?

Answer 1

x = mass of 2nd ball , s = velocity of 2nd ball after collision

in an elastic collision , momentum and kinetic energy are both conserved

m v = -0.300 m v + x s ... s = (0.700 m v) / x

m v^2 = (m .09 v^2) + x s^2 ... .91 m v^2 = x s^2 = 0.490 m^2 v^2 / x

.91 x = 0.490 m