1. The problem statement, all variables and given/known data Is it necessary to have a normal reaction whenever 2 surfaces are in contact with each other? 3. 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"???