Let me imagine a box placed on a table. It has got no acceleration. If I were a person who trusted Newton's laws then I would argue that the net force on the box should be zero. Now in another situation I am an observer outside the Earth and I see that the box is rotating along with the earth, so it should have a centripetal acceleration and gravity provides it...but in the previous case, gravity was canceled by the normal reaction. So shouldn't the centripetal force also be zero. Please explain where I went wrong.