inertia- the tendancy of an object to stay in motion at the same speedand in the same direction.
Newtons Third Law of Motion- (my favorite) it states that "for every action there is an opposite and equal reaction"
Newtons law of universal gravitation- the bigger the object the more gravitational pull it has, that is why the moon goes around the Earth.
Action and Reaction forces- An action force is the movement being done to an object. the reaction force is the event of force that happens. here is an example when you jump in the water a giant splash comes up (you jumping in the pool is the action) (the splash is the reaction force)