So in class today we were talking about Normal Force, and I was really confused on one diagram. Here is a link about the question, but I don't understand why n<mg because if it is less than mg wouldn't that make it go through the earth? not sure but help understanding would be great thanks! http://www.colorado.edu/physics/phys1110/phys1110_sm11/ConceptTests/pdf/Lecture6_Using%20Newton_FreeBodyDiagrams_Normal_tension_gravity.pdf [Broken] And if the link doesn't work the question is, a car traveling at a constant speed goes over a hill, at the top of the hill what is the normal force? Thanks for the help!