In order to understand better why the rock would move at a certain point, I have tried to research a bit more into the idea of inertia and the effect this would have on the movement of the rock.
Here is a website explaining clearly the idea of inertia...
http://www.physicsclassroom.com/class/newtlaws/u2l1b.cfm
Here is a website explaining clearly the idea of inertia...
http://www.physicsclassroom.com/class/newtlaws/u2l1b.cfm
