Strength of Materials(41-60)

Updated: Apr 9, 2020




41.Rate of change of bending moment is equal to shear force

42. The diagram showing the variation of axial load along the span is called

thrust diagram

43. The difference in ordinate of the shear curve between any two sections is equal to the area under load curve between these two sections plus concentrated loads applied between the sections

44. The variation of the bending moment in the portion of a beam carrying linearly varying load is cubic


45. The maximum bending moment due to a moving load on a fixed ended beam

occurs at a support


46. A cantilever beam AB of length / carries a concentrated load W at its midspan C. If the free end B is supported on a rigid prop, then there is a point of contraflexure between A and C

47. A prismatic beam fixed at both ends carries a uniformly distributed load. The

ratio of bending moment at the supports to the bending moment at mid-span is

2.0

48. The relationship between the radius of curvature R, bending moment M and

flexural rigidity El is given by M=EI/R


49. A beam of overall length I with equal overhangs on both sides carries a

uniformly distributed load over the entire length. To have numerically equal

bending moments at centre of the beam and at supports, the distance between the supports should be 0.586 l


50. A prismatic beam of length I and fixed at both ends carries a uniformly distributed load. The distance of points of contraflexure from either end is

0.211 l


51. A simply supported beam of length I carries a load varying uniformly from zero

at left end to maximum at right end. The maximum bending moment occurs at a

distance of 1/√3 from left end


52. If a cantilever beam carries a uniformly distributed load over its entire length, then shapes of shear-force diagram and bending-moment diagram respectively are triangle and quadratic parabola


53. A portion of a beam between two sections is said to be in pure bending when there is constant bending moment and zero shear force


54. The ratio of width to depth of a strongest beam that can be cut out of a cylindrical log of wood is 1/√2


55. Of the several prismatic beams of equal lengths, the strongest in flexure is the one having maximum section modulus

56. Of the two prismatic beams of same material, length and flexural strength, one is circular and other is square in cross section. The ratio of weights of circular

and square beams is 1.118


57. A flitched beam consists of a wooden joist 150 mm wide and 300 mm deep

strengthened by steel plates 10 mm thick and 300 mm deep one on either side of the joist. If modulus of elasticity of steel is 20 times that of wood, then the width of

equivalent wooden section will be 550mm


58.Maximum shear stress in a circular cross section is 4/3 qav


59.A beam of rectangular cross-section is 100 mm wide and 200 mm deep. If the section is subjected to a shear force of 20 kN, then the maximum shear stress in the section is 1.5 N/mm2


60.





If the maximum flexural stress in joist of the flitched beam shown timber in Fig.10.3 is 7 N/mm2, then the maximum stress reached in steel is

70 N/mm2

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