Is it necessary to have a normal reaction whenever 2 surfaces are in contact with each other?
The Attempt at a Solution
I thought the answer was "no". But my book says "yes".
I can support my answer with an example:
the normal force between the surface of a block and the floor of a freely falling lift under gravity is zero.
Please help me. Does my book author takes the molecular level forces into account when he goes on to say "yes"???