Answer:
The magnitude of the change in gravitational potential energy of the earth-athlete system over the course of the race is 643,536Joules
Step-by-step explanation
Potential energy is one of the form of mechanical energy and it is defined as the energy possessed by a body due to virtue of its position. When the body is under gravity, it possesses an energy called the gravitational potential energy.
Gravitational potential energy is expressed as shown:
GPE = mass × acceleration due to gravity × height
Given mass of athlete = 80kg
height covered = 820m
acceleration due to gravity = 9.81m/s
GPE = 80×9.81×820
GPE = 643,536Joules