Recent content by Negi Magi

"As the ball gets deeper under the surface of the Earth, the layers above it stop exerting gravitational force, and all that matters is the mass underneath." How to justify this sentence is true?

Homework Statement See the attached picture. The big disk is fixed on the ground, and the small disk move under the gravity. There is no friction between two disks. When will the small disk is no longer touch the big disk? Just measure the distance between the center of the small disk and the...

There is a question: If we dig a channel from the North pole of the Earth to the South pole of the Earth, then we release a ball into this channel from the North pole, what will be the motion of this be like? I think this question is related to the inner gravitational field of the Earth

I really need it now! Someone helps me

Thank you very much, that's very helpful

Oh,yes. When I first saw this question, I have no idea about that. However, now I know that this question is a kind of Fermi questions, which need appropriate estimation. But the problem is that I do not know how to start. There is another Fermi question, " How many Piano Tuners in New York? "...

Yes, I mean the "grains of sand" I do not really understand your first two questions.

1. How many sands on the earth? 2. Hints: Using the Fermi estimation 3.