The equation is
W 1 L 1 þW 2 L 2 ¼w 1 l 1 þw 2 l 2
80 ð 8 Þþ 84 ð 4 Þ¼ 95 ð 8 Þþ 75 ðxÞ
640 þ 336 ¼ 760 þ 75 x
976 ¼ 760 þ 75 x
976 760 ¼ 760 760 þ 75 x
216 ¼ 75 x
216
75
¼
751 x
75
2 : 88 ¼x
Sam needs to sit 2.88 feet from the fulcrum.
EVALUATION: Check the equation:
W 1 L 1 þW 2 L 2 ¼w 1 l 1 þw 2 l 2
80 ð 8 Þþ 84 ð 4 Þ¼ 95 ð 8 Þþ 75 ð 2 : 88 Þ
640 þ 336 ¼ 760 þ 216
976 ¼ 976
Fig. 16-5.
LESSON 16 Solving Lever Problems 177