I don't understand why the physics book defines the centripetal force and gravitational force acting in different directions. N - m*(acceleration of gravity) = -m*r*w^2 N = m*(acceleration of gravity) - m*r*w^2 Why don't the acceleration of gravity and centripetal acceleration add up? I would think that the normal force would be greater near the equator since there is both gravitational and centripetal forces in the same direction. But the book says the opposite. Thanks for the help.