A 40 lb. child sits at one end of a teeter-totter (lever) which is 12 feet long and has the fulcrum (point of balance) in the center as shown. How many feet from the fulcrum should a 60 lb. child sit so the teeter-totter will balance?



To help you answer this question, examine the table below and discover one of the properties Archimedes discovered about levers. The values in the table cause a lever to be in balance.

D1(Distance child 1 is from the fulcrum)	W1(Weight of child 1)	D2(Distance child 2 is from the fulcrum)	W2(Weight of child 2)
5 ft	40 lbs	2 ft	100 lbs
6 ft	70 lbs	4 ft	105 lbs
3 ft	80 lbs	4 ft	60 lbs
4 ft	75 lbs	6 ft	50 lbs

Using your discovery, fill in the missing values below.

D1(Distance child 1 is fromthe fulcrum)	W1(Weight of child 1)	D2(Distance child 2 is from the fulcrum)	W2(Weight of child 2)
4 ft	55 lbs	5 ft
5 ft		6 ft	125 lbs
	60 lbs	3 ft	40 lbs
6 ft	115 lbs		138 lbs

Summarize your discovery by writing a formula expressing the relationship between D1, W1, D2, and W2. This is Archimedes’ Law of the Lever.