60 MOTION AND LOCOMOTION 



arm and 10 in. for length of weight arm. Note the muscle pull 

 for various weights. 



3) Set up apparatus to illustrate action of triceps, when 

 "heel" of hand is used for pushing, as in pushing up a weight. 

 Allow V 2 in. for length of power arm and 10 in. for length of 

 weight arm. 



Problems: (Each pupil should use his own weight and make 

 the necessary measurements on himself or on a skeleton.) 



1, a) How much force do the calf muscles exert in raising 

 heel from floor, when person is standing on one foot, if the 

 ratio between power and weight arms is assumed to be 1 to 3 ? 



b) How much is the pressure in ankle joint? 



2, a) How much does the biceps pull when, by flexing fore- 

 arm, 15 Ibs. are raised in palm of hand, if ratio between arm 

 lengths is assumed to be 1 to 7 ? 



b) How much is the pressure in elbow joint? 



