EXPERIMENTS WITH LEVERS 



59 



forward much more rapidly against the resistance of 

 the air. The amount of power required is therefore 

 much greater than for walking. 



EXPERIMENTS AND DEMONSTRATIONS 



Apparatus: Lever apparatus made with 2 spring scales 

 weighing up to 24 Ibs. and 2 pieces of lath arranged as shown in 

 diagram. 



1) Set up apparatus for foot leverage, assuming 1 in. as 

 distance from ankle joint (fulcrum) to insertion of tendon of 



i Biceps 



ift.ftA6l.tfc t'4 fa A .'. 



! Triceps 



Triceps 

 Biceps 



ill of foot 



If muscles 



FIG. 49. Lever apparatus made of lath and spring balances arranged for foot as 

 acted on by calf mut>clef in rifingon toe. The arrangements for arm when flexed 

 by biceps 'muscle and extended by triceps are indicated by the dotted arrows. 

 (Figures indicate half inches.) 



calf muscles (power arm), and 3 in. from ankle joint to ball of 

 foot (weight arm). Use various body weights (taking 1-100 

 of body weight as weight) and determine the muscle pull 

 necessary to balance them. 



2) Set up apparatus to illustrate action of biceps when a 

 weight is lifted in hand, allowing l 1 /^ in. for length of power 



