[SOLVED] basic question about gravity This is just a simple concept question. A person is moving on a ferris wheel around in a circle and the magnitude of the work done on them moving from top to bottom is W=2*g*m*r where m=mass and r-radius of ferris wheel. When plugging in the numbers into the equation, the answer would always be positive correct because gravity is down, positive and mass is positive and the radius is positive. For some reason I am thinking that maybe the gravity would be negative when moving down. I would appreciate any help.