Newton's Third Law states that for every action force, there is a reaction force. So take a classical problem with a basketball player. The earth has a gravitational force on the player, and thus player exerts an equal and opposite force on the earth. The player is stationary. My first question is, is this equal opposite force on the earth exerted by the player the normal force (yes, it would be numerically equivalent, but by definition)? Suppose the player decides to jump. Since there is a net force in play due to a certain net acceleration the player, things are no longer at an equilibrium. Does this mean that upon jumping, the player exerts more force on the earth (floor) than the earth exerts on the player? And if so, how is this variation from Newton's Third Law possible? Thank you beforehand.