The solution is g=v022h.
By gmmr 2 = mg
Know that the quality of the earth is; M=v02R22Gh
According to the theorem of kinetic energy, we can know the work that the bouncing ball does to the children during the take-off: W= 12mv02.
Answer: (1) What the bouncing ball did to the child during this take-off: W= 12mv02.
(2) The mass of the earth is: M=v02R22Gh.