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
