It can help because when people say "I have a Hypothesis" so in the ancient language it would mean "I have a 'to suppose'" or "I suppose." So the person supposes, or guesses the answer based of the information they got.
Answer:
you meant what are the main sources
they are: fossil
clean energy
energy storage
hydrogen& fuel
electric power
Answer:
Gravity is considered to be one of the universal forces inherent of nature itself. Gravity is an attractive force between objects, which is proportional to the mass of the objects and inversely proportional to the distance between them. Gravity is what help planets follow an elliptical orbit, and is the reason why we can keep our feet on the surface of the earth.