248 APPLIED SCIENCE 



5. A piece of steel plate with a cross-section Y^ in. X 1 in. 

 pulled apart in the testing machine requires a load of 29,600 Ibs. 

 What load would a piece with 1 in. cross-section require? 



^ 6. A piece of steel % in. square 



pulled apart in the testing machine requires 

 a load of 6000 Ibs. What is the ultimate 

 tensile strength of this material? 



7. There are four wrought iron bolts in 

 the press shown in Fig. 106. If the 

 capacity of the press is 10,000 Ibs., what 

 size should the bolts be? 



FIG. 106.-Letter Press. 8 ' What must be the diameter of a 

 steel piston rod if the piston is 18 in. in 

 diameter and the steam pressure is 110 Ibs. per square inch? 



Area of piston = 18 2 X .7854 = 254.47 



254.47 X 110 = 27,991.7 Ibs. 

 or, about 28,000 Ibs., which is the stress in the rod. 



9. What size piston rod must we use if the piston is 22 in. in 

 diameter and the steam pressure is 150 Ibs.? 



