B3-14
Counterintuitive demonstration involving pulley system
A frame containing the pulley and the lower scale hangs from the upper scale as photographed. The initial weight of the lower scale, pulley, and frame together is about 5 Newtons, as read on the upper scale; initially the lower scale reads zero. The difference in resultant force due to the pulley can be observed from the difference in the change of the two scales.
FS2