What potential energy relative to the ground does a person weighing 80 kg at an altitude of 20 m have?

Answer: 16 kJ.
Explanation of the solution to the problem: to solve this problem, you must use the following formula:
Ep = m * g * h, where m is the mass of the body in kg, g is the acceleration of gravity, g = 10 N / kg, h is the height at which the body is located.
Substituting the values known from the condition of the problem, we obtain:
Ep = m * g * h = 80 * 10 * 20 = 16000 J = 16000/1000 = 16 kJ.