How do you find the effective force of Gravity when at a particular latitude? I keep trying to figure it out, but I can't seem to wrap my head around it. I understand that some small portion of the force of gravity goes towards your centripetal acceleration at certain latitudes, but I can't seem get the idea, since you seem to have three unknowns, but only two equations. For example (45 degree latitude): You are not moving in the y-direction, so the y-component of your weight must be equal to the y-component of your normal force; http://ffanxii4ever.googlepages.com/hp1.bmp/hp1-medium;init:.jpg [Broken] and then the net force in the centripetal acceleration is: http://ffanxii4ever.googlepages.com/hp2.bmp/hp2-medium;init:.jpg [Broken] But you only have these two equations, but you have three variables, the normal force, the acceleration of gravity (and as a result the force of gravity) and the angle that the normal force is at (it is offset from the force of gravity). Does anyone have any idea as to what I am missing, that is making me incapable of understanding this? Thanks.