Elastic Collisions: "A charging bull elephant with a mass of 5400kg comes directly toward you with a speed of 4.30 m/s. You toss a 0.150 kg ball at the elephant with a speed of 8.11 m/s. "
(a) When the ball bounces back toward you, what is its speed?
(b) How do you account for the fact that the ball's kinetic energy has increased?

**The answer in the back of the book for (a) is 17 m/s.**

Question

Elastic Collisions: "A charging bull elephant with a mass of 5400kg comes directly toward you with a speed of 4.30 m/s. You toss a 0.150 kg ball at the elephant with a speed of 8.11 m/s. "
(a) When the ball bounces back toward you, what is  its speed?
(b) How do you account for the fact that the ball's kinetic energy has increased?

**The answer in the back of the book for (a) is 17 m/s.**