376_Physics ProblemsTechnical Physics

# 376_Physics ProblemsTechnical Physics - 378 P12.69 Static...

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378 Static Equilibrium and Elasticity P12.69 Member AC is not in pure compression or tension. It also has shear forces present. It exerts a downward force S AC and a tension force F AC on Pin A and on Pin C . Still, this member is in equilibrium. FF F F F xA CA C A C =− ′=⇒ = 0 25.0 m A 25.0 m 14.7 kN C F AC F AC S AC S AC τ A = 0: −+ = 14 7 25 0 50 0 0 .. . kN m m af a f a f S AC or ′= S AC 735 . k N FS S yA C A C + = ⇒= 14 7 7 35 0 7 35 . kN kN kN Then SS AC AC =′ and we have proved that the loading by the car is equivalent to one-half the weight of the car pulling down on each of pins A and C , so far as the rest of the truss is concerned. n A n E A B C E D 25.0 m 14.7 kN 75.0 m For the Bridge as a whole: A = = = + = = 14 7 25 0 100 0 367 14 7 3 67 0 11 0 . . kN m m kN kN kN kN a f a f n n Fn n E E A At Pin A : FF F F B AB C AC + °= = ° = = 110 300 0 0 637 s i n . . .c o s . . kN kN kN compression kN kN tension bg a f At Pin B : F F yB C BC xB D BD °− = = = 600 0 424 0 849 .s i n i n . . o s . o s . . kN kN tension kN kN kN compression At Pin C : F F yC D CD x CE CE + °
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## This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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