Answer:
831.4 J
Explanation:
Info given:
mass adult: 82.5kg
mass child: 14.7kg
height of wall: 1.25m
g = 9.81m/s^2
PE = mgh
For adult:
mgh = (82.5kg)(9.81m/s^2)(1.25m) = 1011.65 J
For child:
mgh = (14.7kg)(9.81m/s^2)(1.25m) = 180.25 J
Difference in PE: 1011.65 J - 180.25 J = 831.4 J