Where is the power applied?
The power is applied by the hand to the long arm of the lever.
How may a see-saw be made?
A see-saw may be made by placing a plank or a board across a rail in a fence, so that it will balance.
Is the see-saw, as shown in [Fig. 43], an example of the lever?
Yes; the see-saw is an example of the lever.
Fig. 43.
What are the parts of the plank on each side of the fence-rail called?
They are called the arms of the lever.