D; solar system, because the planets are inside it.
I would say B but I have no clue
Answer:
You could move something across the Earth with a little push. It would make fuel really efficient on those pathways. You could make a floor that is impossible to walk on. Everybody would just fall without traction.
Explanation:
Answer: 
Explanation:
Given
Mass of the elevator is 
Time period of ascension 
cruising speed 
Distance moved by elevator during this time
Suppose Elevator starts from rest

Distance moved

Gain in Potential Energy is

Average power during this period is
