PURPOSE: To show addition of forces along a line.

DESCRIPTION: Each scale shows the total weight of those hanging below it plus any force exerted downward on the lower scale. The bottom scale measures its own weight, about 3 Newtons. In the picture above, a downward force of 9 Newtons is being exerted by Jack's hand at the bottom of the picture, so the scales read (bottom to top) 12N, 12N, 15N, and 18N.

SUGGESTIONS:

REFERENCES: (PIRA 1J30.23)

EQUIPMENT: Four dynamometers on stand with lead brick weight.

SETUP TIME: 5 min.