Now we need to figure out what are the relations between , , and . and have to have the same magnitude. This was discussed earlier when we considered examples with forces. If moves up one ince, must move down the same distance. But their directions are opposite. Therefore

If is positive then the pulley spins around in the counterclockwise direction. By the right hand rule, if you curl you right hand around the pulley in the direction of motion, then your thumb sticks out of the page, which is the positive direction. Therefore

or

Sun Feb 23 15:54:50 PST 1997