QUESTIONS AND PROBLEMS CHAPTER IV. 



65 



1. Upon what equation of equilibrium is the law of the 

 lever based? 



2. If a beam is supported at its quarter point what must 

 be the ratio of the load at the end of the short arm to that at the 

 end of the long arm when the beam is balanced, neglecting the 

 beam's own weight? If the beam is 20 ft. long and weighs 50 Ibs. 

 per ft., what load, at its end, will be required to balance it. 



3. What are the reactions for a beam 20 ft. long, supported 

 at its ends, weighing 100 Ibs. per ft., and having a load of 15000 

 Ibs. at 5 ft. from one end? 



4. Find R l and JR 2 , Fig. 33, for P = 20000 Ibs. Also for 

 the same panel load at each of the joints 6, c, d, and e. 



5. Draw a truss of eight equal panels similar to that of 

 Fig. 33 and number the intermediate joints, from right to left. 

 Find the values of RI, for a load P at 1, at 1 and 2, at 1, 2, and 

 3, etc. 



6. If the truss of Fig. 33 consists of 5 panels at 20 ft. each, 

 what will be the panel loads at c and d produced by a load 44 ft. 

 from R\, so placed upon the floor of the bridge that 6000 Ibs. will 

 be carried to one truss? What will be the reactions produced at 

 the ends of the truss? What will be the reactions produced at 

 the ends of a girder having a span of 100 ft., by a load of 6000 

 Ibs. located 44 ft. from one support? 



7. Show how the construction of Fig. 39 will be modified 

 for the wind load on the other side of the roof. 



8. What will be the horizontal and vertical components of 

 the reactions for a symmetrical three-hinged arch having a span 

 of 160 ft., and a rise of 40 ft., for a load of 80000 Ibs. at 40 ft. 

 from one support. (Apply the equations of equilibrium and do 

 not use formulas). 



9. Take the figures representing the loads in Fig. 43 as 

 thousands of pounds, and find the reactions when these loads are 

 combined with a uniform load of 400 Ibs. per foot. 



10. In the above case, what will be the shear at 15 ft. from 

 .4? At 7 ft. from C? 



11. Find all the reactions for Fig. 49 when P = 30000 Ibs., 

 ft = 20 ft., and 6 = 16 ft. 



12. How would you find the reactions in Figs. 51 and 53 

 when the panel loads and panel lengths are unequal? 



