Answer = 20.5 J
The work done on the ball as it falls through the air can be found by using the gravitational potential energy (GPE) equation. You use this equation because work is done on the ball to move the ball from one place to another due to gravity:
GPE = Mass x Gravitational field strength x Height
The values given are:
Mass = 0.11 kg
Height = 19 m
Gravitational field strength (gravity) = 9.81 m/s
Substitute the values into the GPE equation:
GPE = 0.11 x 9.81 x 19
GPE = 20.5 J