QUESTIONS AND PROBLEMS. CHAPTER VII. 143 



to a moment diagram? What corresponds to the load in the 

 former case? 



15. In what case is the deflection due to shear not 

 negligible? 



16. What percentage of the total deflection is due to shear 

 in a timber beam 12"xl2", having a span of 16 ft. and carrying 

 a load P at the middle? E^ = \E. Ans. 1.16%. 



17. What is the total elastic resilience of the girder shown 

 in Fig. 91 if E = 29000000, and the elastic limit of the material 

 is 32000 Ibs.? Are there any factors affecting the result pre- 

 judicially? Ans. 36400 in. Ibs. 



18. What is the most economical way of increasing the 

 moment of resistance of a beam? The resilience? 



19. For the same live load, which has the greater resilience, 

 a short beam or a long beam, if the maximum stress is the same 

 in both? 



20. Why does a bridge vibrate? 



21. Analyze the beam shown in Fig. 103 in the manner 

 shown in Fig. 93, and compare the maximum moments in the 

 two cases. 



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BFPT, of APPLIED MECHANI 



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