gravity and air resistance questions

Junior high studetn needs help with understanding concept behind grvaity. Help with following basic questions in simple terms please. 1. Imagine you started to walk towards the west. Imagine that you can walk forever and that you can even walk on water. If you walk in the same direction forever, what will happen? Where will you end up? 2. Imagine that there is a big hole that tunnels al the way through the center of the earth vertically. If you drop an apple down this hole what would happen? explaine answer using terms of gravity, air resistance. 3. Usiing the same thought from the above problem, only the tube is running horizontally through te center of the earth, what would happ... click for more

Black hole accretion rate problem

Hello See attached for full question. It is basically a problem asking me to manipulate an equation using the Eddington accretion rate and calulating some of the constants. i have made a few notes and would appreciate any explanations of the maths required. thank you