You are lawn bowling and bowl a ball with a speed of 6.18 m/s. Unfortunately, your ball hits a large rock of mass 470 g, resulting in a perfectly elastic collision. If the final velocity of the ball after the collision is -3.43 m/s, what must the mass of the ball be?

Answer 1

So the large rock must move..
energy: 1/2 M*6.18^2=1/2 M*(-3.43)^2 + 470*Vrock^2
momentum: M*6.18 = 470*Vrock+ M (-3.43)
solving for M, start with second equationi
M(6.18+3.43)=470Vrock
Vrock= M (9.61)/470 Put that into the energy equation, then solve for Mass of ball M.