78 Our Surroundings 



13. Is more work done in lifting a 200 Ib. weight 70 ft. in one minute 

 than in lifting a 50 Ib. weight 280 ft. in the same time? 



14. Compare the work done in lifting 2,000 Ib. a distance of 5 ft. in one 

 minute with that done in lifting the same weight the same distance 

 in four minutes. 



15. Explain the principle on which this statement is based: Water seeks 

 its own level. 



PROJECTS 



1. Construct a small water wheel. 



2. Make a labeled map showing the rivers in your state that produce, 

 or might produce, water power. 



OUTDOOR OBSERVATION 



1. Observe and report on effects of ice on streams and pools. 



2. Visit, observe and report on the nearest water supply system. 



3. Follow up the nearest very small stream from mouth to source. Re- 

 port on how it is fed, how it drains land, and how its banks have 

 been affected by the flowing water. 



REFERENCES 



The Story of Agriculture in the United States Sanford 



The Conservation of Energy Stewart 



