ELASTIC DEFORMATION 



44. A wooden post 4 inches square and 2J- feet high sustains a 

 compressive load of 10 tons. How much will the post be shortened ? 

 Find the proportion of this shortening to that produced by loading 

 the post to its elastic limit. 



45. Determine the length of a 1^-inch round wrought-iron bar, 

 which would elongate 0.1 inch under a load of 8000 pounds sus- 

 pended from its lower end, and the factor of safety. 



46. By what proportion of its own height will a wrought-iron block 

 be shortened if loaded to one half its elastic limit, and what will be 

 the factor of safety ? 



47. A bar of structural steel 1 inch in diameter is under successive 

 tensions of 25,000, 30,000, and 35,000 pounds. Calculate the unit- 

 elongations in each case, and determine by this means which loads 

 give a stress greater than the elastic limit of the bar. 



48. How much will a steel punch 2 inches square and 4 inches 

 long, of uniform size, be shortened by the force required to punch a 

 2-inch square hole through a wrought-iron plate ^ inch thick ? 



49. How many 1-inch square rods of wrought-iron would be needed 

 for the suspension of a platform loaded with 20 tons, if the stretching 

 of the rods be limited to one half their elongation at the elastic limit? 

 Each rod bears equal shares of the load. 



50. A wrought-iron tie rod is | inch diameter. How long must it 

 be to lengthen | inch under a steady tension of 5000 pounds ? 



51. A wooden rod 3 inches in diameter is elongated 0.05 inch by 

 a force of 2000 pounds. What was its original 



length ? 



52. How much will a hundred-foot steel tape, 

 ^ inch wide and jfo inch thick, stretch under a 

 pull of 50 pounds ? 



53. A rectangular timber tie is 12 inches deep 

 and 40 feet long. Find the proper thickness of 

 the tie, so that its elongation under a pull of 

 270,000 pounds shall not exceed 1.2 inches. 



54. A flanged cylinder 10 inches inside di- 

 ameter and 10 feet long contains steam at a pressure of 150 pounds 

 per square inch. The heads of the cylinder are held against the 

 flanges by a single wrought-iron bolt 1 inch in diameter, extending 



bJ 



