1. The problem statement, all variables and given/known data A vertical spring is fixed on a table. A book is put on the spring. The book compresses the spring until static equilibrium is reached. Question: Is there a normal force exerted by the spring on the book? Why or why not? 2. Relevant equations 3. The attempt at a solution I think there is because normal force is a contact force. As long as two bodies are in contact, I think it exists. But I never see books mention normal force in this kind of problem.