I was looking for some clarifications on Newton's 3rd Law.
I've heard that a book resting on the surface of a table is not an example of Newton's 3rd law. The Earth's gravity pulls down on the book and the resultant force is not the support or normal force but rather the books pull on the Earth. If this is the case, What is the reaction force of the normal force?
Does this mean that Newton's 3rd Law requires the opposite forces to be of the same type? Consider a rocket fired into space. What is the reaction force of the weight of the rocket? My teacher said that the reaction force must be the gravitational force of the rocket on the Earth as this is the same type of force.
What does same type of force even mean? Is there some definition of Newton's 3rd Law that can help me clearly understand these problems? Any online resources or pdfs would help.