Final answer:
The mechanical energy of the falling ball is 15 J, which is the sum of its potential energy and kinetic energy.
Step-by-step explanation:
The mechanical energy of an object is the sum of its kinetic energy and potential energy. In this case, the falling ball has a potential energy of 5 J and a kinetic energy of 10 J. Therefore, its mechanical energy is the sum of these two values.
To calculate the mechanical energy, simply add the potential energy and kinetic energy: 5 J + 10 J = 15 J. So, the ball's mechanical energy is 15 J.