Answer: It wouldn't be as modern as today is we would be back to using oil and other things from back then there wouldn't be cars everything would be less machined.
B- the acceleration is greater for the more massive rock
If Fg=mg=ma and, Fg(planetX)=1/5Fg(earth)
then the time would be 5x of the time as gravity is acceleration. So 3.9s*5=19.5s
As the force of gravity is less, then the acceleration of masses is also less, therefore it will take more time for the object to fall by the factor of the force of gravity difference
600 watts may be your answer:)
