BLOCKS

one end of the cord at C and attach the spring balance to the other end
at P. Hang a 2 Ibs. weight at TF. The suspended weight of 2 Ibs. is
supported half by the cord at C and half by the hand at P as indicated by
the balance registering 1 Ib. The effort exerted by the hand at P is just

Fig 82.

Fig 84.

Pulley Purchases.

one half of the weight to be supported. The mechanical advantage is
said to be 2 because a power of 1 Ib, balance^ a weight of 2 Ibs. It will
be noted that there are two parts of the cord at the moving pulley and
this number gives the mechanical advantage gained by this machine.
If the weight be now overcome by exerting more power at P so