A nearly massless one of these objects is used to 
A nearly massless one of these objects is used to hold the weights for an Atwood machine. One mass pulls another across a table using the horizontal version of this device. A single fixed-axis one has a mechanical advantage of 1, while adding more of them will often increase the mechanical advantage if friction is ignored. (*) For 10 points, name this simple machine that uses an axle and a rope to lift objects.
A nearly massless one of these objects is used to hold the weights for an Atwood machine.
{pulley} [or {sheave}]