Explanation:
The potential energy of an object can be calculated as the sum of its kinetic and gravitational potential energy. At its highest point, the ball has zero kinetic energy, so the potential energy is equal to its gravitational potential energy.
The gravitational potential energy of an object is given by:
PE = m * g * h
where m is the mass of the object (7 kg), g is the acceleration due to gravity (9.8 m/s^2), and h is the height above a reference point. In this case, the reference point is the ground, so h = 100 m.
Substituting in the given values, we find:
PE = 7 * 9.8 * 100 = 686 J
This is the potential energy of the ball at its highest point.