Answer:
See below
Step-by-step explanation:
The kinetic energy of the ball is = to the amount of work he did
1/2 mv^2 = 1/2 * .5 kg * (6 m/s)^2 = 9 J
1/2 ( .5)( 7.46)^2 - 9 = 4.9 j
The Pontential energy of the ball ( the height of the ball when launched) was converted to vertical velocity adding to the increase in velocity as it hit the floor.... so AFTER it was launched ...GRAVITY did the work. ( It was actually Potential Energy created when the ball was lifted to launch height BEFORE launch)