Hw1 - Normal Stress: 1 Bars CE and DE in the truss have a...

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Unformatted text preview: Normal Stress: 1 Bars CE and DE in the truss have a cross-sectional area A=25cm'. Find the normal stress in each of these bars. Solution Using the method ofjoints. and the fact that angle DEC=53.13°‘ we have ch Sin(53.13°)=20kN. then Fc5=25.00kN. Then. the stress in bar CE 15 A C l'. similarly. FDE=-Fag Cos(53.13°)=-15.00kN. and 0' DF : I‘m“ = ——152 = —6, 000kPa (compression) ' Am: 25*1/100 Normal Stress: 3 Beam AB is vertical and the 20KN load 20“ is applied in the y-direction. Find the stress in the two identical cables, of diameter d=2cm. Solution Due to symmetry, the two cables will be subjected to identical tensile stress Coordinates of point B (x,y,z) in meters: (0,0,5) Coordinates of point C: (-l,-4,0) Vector BC: (-l,—4,-5) Magnitude of vector BC: (—1)2 + (—4)2 + 52 = 6.48m _ _ . _ —l —4 —5 Unit vector in direction BC: —,—,— 6.48 6.48 6.48 Let Fnc denote the magnitude of the force in cable BC. Then the component of this force in the y- 4 direction is —mFBC . Then for equilibrium in the y-direction (since the component of the force in BD is the same as the force in BC) 4 2—F =20kN—>F =16.2kN. 6.48 3° “C Then, aBC =Ffi=fl=srs923kpa A n-0.022/4 Normal Stress: 6* A taw truck is using a cable to pull the classic car up a 15° hill. If the classic car weighs 4000 lbs and the cable has a diameter of 3/4 inch, find the stress in the cable when the truck comes to a stop while on the hill. Ignore friction between the car and the pavement. ...
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Hw1 - Normal Stress: 1 Bars CE and DE in the truss have a...

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