Where must the fulcrum be when one boy is heavier than the other?
The fulcrum must then be nearest to the heavier boy, so that they may balance.
Does it require much force to play at see-saw?
No; when the see-saw is balanced, a very little force will cause it to move up and down.
Of what use is a pair of scales?
A pair of scales is very useful in weighing different substances.
Fig. 44.
Are the scales, as shown in [Fig. 44], an example of the lever?
The scales are an example of the lever.