MOTION. 23 



6. Why is it easier to sit with one leg crossed over the other? 



7. What is the effect on muscles of light clothing? 



8. How may the arms be used to illustrate the three kinds of 

 levers ? 



9. Analyze and explain jumping, hopping, etc. 



10. What is "curvature of the spine"? How caused and how 

 avoided ? 



1 1 . What makes people bow-legged ? 



12. Why are the sides of the body often sore after walking on icy 

 pavements ? 



