f you
wanted to move the pail with the least effort, where would you
put your hand?

EXPERIMENT 20. Use a pair of long-bladed shears and fold a
piece of cardboard once to lie astride your own or some one
else's finger. Put the finger, protected by the cardboard,
between the two points of the shears. Then squeeze the handles
of the shears together. See if you can bring the handles
together hard enough to hurt the finger between the points.

Now watch the shears as you open and close the blades. Which
move farther, the points of the shears or the handles? Which
move faster?

Next, put the finger, still protected by the cardboard,
between the _handles_ of the shears and press the points
together. Can you pinch the finger this way harder or less
hard than in the way you first tried?

Do the points or handles move farther as you close the shears?
Which part closes with the greater force?

[Illustration: FIG. 29. You cannot pinch hard enough this way to
hurt.]

[Illustration: FIG. 30. But this is quite different.]

EXPERIMENT 21. Use a Dover egg beater. Fasten a small piece
of string to one of the blades, so that you can tell how many
times it goes around. Turn the handle of the beater around
once slowly and count how many times the blade goes around.
Which moves faster, the handle or the blade? Where would you
expect to find more force, in the cogs or in the blades? Test
your conclusion this way: Put your finger between the blades
and try to pinch it by turning the handle; then place your
finger so that the skin is caught between the cogs and try to
pinch the finger by turning the blades. Where is there more
force? Where is there more motion?

EXPERIMENT 22. Put a spool over the nail which was your
fulcrum in the first two experiments. (Take the stick off
the nail first, of course.) Use this spool as a pulley. Put a
string over it and fasten one end of your string to the pail
(Fig. 32). Lift the pail by pulling down on the other end of
the string. Notice that it is not harder or easier to move the
pail when it is near the nail than when it is near the floor.
When your hand moves down from the nail to the floor, how far
up does the pail move? Does the pail move a greater or less
distance than your hand, or does it move the same distance?

Next fasten one end