A charging bull elephant with a mass of 5500 kg comes directly toward you with a speed of 4.70 m/s . You toss a 0.160-kg rubber ball at the elephant with a speed of 7.50 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?

v2 = - 16.899 m/s

velocity of ball increases so that the kinetic energy of the ball increases.

Explanation:

given data

mass of elephant, m1 = 5500 kg

mass of ball, m2 = 0.160 kg

initial velocity of elephant, u1 = - 4.70 m/s

initial velocity of ball, u2 = 7.50 m/s

solution

we consider here final velocity of ball = v2

so  collision formula is express as for v2

     .................1

put here value and we get

solve it we get

v2 = - 16.899 m/s

here negative sign shows that the ball bounces back towards you

and

here we know the velocity of ball increases so that the kinetic energy of the ball increases.

and due to this effect, it will gain in energy is due to the energy from the elephant mass