MCQ  ON STRENGTH OF MATERIALS

1.Whenever some external system of forces acts on a body, it undergoes some deformation. As the body undergoes some deformation, it sets up some resistance to the deformation. This resistance per unit area to deformation, is called

• strain
• stress (Ans)

• pressure

• modulus of elasticity

2.The deformation per unit length is called

• tensile stress

• compressive stress

• shear stress

• strain (Ans)

3.The unit of strain is

• N-mm

• N/mm

• mm

• no unit (Ans)

4.When a body is subjected to two equal and opposite pulls, as a result of which the body tends to extend its length, the stress and strain induced is

• compressive stress, tensile strain

• tensile stress, compressive strain

• tensile stress, tensile strain (Ans)

• compressive stress, compressive strain

5.When a body is subjected to two equal and opposite forces, acting tangentially across the resisting section, as a result of the body tends to shear off across the section, the stress and strain induced is

• tensile stress, tensile strain

• compressive stress, compressive strain

• shear stress, tensile strain

• shear stress , shear strain (Ans)

6.Hook’s law holds good up to

• yield point

• elastic limit (Ans)

• plastic limit

• breaking point

7.Whenever a material is loaded within elastic limit, stress is…………….. strain.

• Equal to

• directly proportional to (Ans)

• inversely proportional to

8.The ratio of linear stress to the linear strain is called

• modulus of rigidity

• modulus of elasticity (Ans)

• bulk modulus

• poisson’s ratio

9.The unit of modulus of elasticity is same as those of

• stress, strain and pressure

• stress, force and modulus of rigidity

• strain ,force and pressure

• stress, pressure and modulus of rigidity (Ans)

10.When change in length takes place, the strain is known as

• linear strain (Ans)

• lateral strain

• volumetric strain

• shear strain

11.The change in length due to a tensile or compressive force acting on a body is given by

• P.l.A/E

• Pl/AE (Ans)

• E/P.l.A

• AE/Pl

where p=Tensile or compressive force acting on the body

l= Original length of the body,

A= Cross-sectional area of the body, and

E= Young’s modulus for the material of the body.

12.Young’s modulus may be defined as the ratio of

• linear stress to lateral strain

• lateral strain to linear strain

• linear stress ti linear strain (Ans)

• shear stress to shear strain

13.Modulus of rigidity may be defined as the ratio of

• linear stress to lateral strain

• lateral strain to linear strain

• linear stress ti linear strain

• shear stress to shear strain (Ans)

14.The deformation of a bar under its own weight is ………………. the deformation, if the same body is subjected to a direct load equal to weight of the body.

• Equal to

• half (Ans)

• double

15.The elongation of a conical bar under its own weight is ……………. that of prismatic bar of the same length.

• Equal to

• half

• one-third (Ans)

• two-third

16.Strain rosetters are used to

• measure shear strain

• measure linear strain (Ans)

• measure volumetric strain

• relieve strain

17.A bar of length L metres extends by l mm under a tensile force of P. The strain produced in the bar is

• l/L

• 0.1l/L

• 0.01l/L

• 0.001l/L (Ans)

18.The maximum stress produced in a bar of tapering section is at

• smaller end (Ans)

• larger end

• middle

• anywhere

19. Modular ratio of the two materials is the ratio of

• linear stress to linear strain

• shear stress to shear strain

• their modulus of elasticities (Ans)

• their modulus of rigidities

20.The shear modulus of most materials with respect to the modulus of elasticity is

• equal to half

• less than half (Ans)

• more than half

• none of these

21.A rod is enclosed centrally in a tube and the assembly is tightened by rigid washers. If the assembly is subjected to a compressive load, then

• rod is under compressive

• tube is under compressive

• both rod and tube are under compression (Ans)

• tube is under tension and rod is under compression

22.A bolt is made to pass through a tube and both of them are tightly fitted with the help of washers and nuts. If the nut is tightened, then

• bolt and tube are under tension

• bolt and tube are under compression

• bolt is under compression and tube is under tension

• bolt is under tension and tube is under compression (Ans)

23.When a bar is subjected to a change of temperature and its deformation is prevented, the stress induced in the bar is

• tensile stress

• compressive stress

• shear stress

• thermal stress (Ans)

24.Which of the following statement is correct?

• The stress is the pressure per unit area

• the strain is expressed in mm

• hook’s law holds good up to the breaking point

• stress is directly proportional to strain within elastic limit (Ans)

25.The unit of stress in S.I. Units is

• N/mm2

• kN/mm2

• N/m2

• any one of these (Ans)

26.The modulus of elasticity for mild steel is approximately equal to

• 10kN/mm2

• 80kN/mm2

• 100kN/mm2

• 210kN/mm2 (Ans)

27.When a bar of length l and diameter d is rigidly fixed at the upper end and hanging freely, then the total elongation produced in the bar due to its own weight is

• wl/2E

• wl2/2E (Ans)

• wl3/2E

• wl4/2E

28.The length of a conical bar is l, diameter of base is d and weight per unit volume is w.It is fixed at its upper end and hanging freely.The elongation of the bar under the action of its own weight will be

• wl2/2E

• wl2/4E

• wl2/6E (Ans)

• wl2/8E

29.A steel bar of 5 mm is heated from 15oC to 40oC and it is free to expand.The bar will induce

• no stress (Ans)

• shear stress

• tensile stress

• compressive stress

30.When a bar is cooled to -5oC, it will develop

• no stress

• shear stress

• tensile stress (Ans)

• compressive stress

31.A bar of copper and steel form a composite system, which is heated to a temperature of 40oC. The stress induced in the copper bar will be

• tensile

• compressive (Ans)

• shear

• zero

32.The deformation of the bar per unit length in the direction of the force is known as

• linear strain (Ans)

• lateral strain

• volumetric strain

• shear strain

33.Every direct stress is always accompanied by a strain in its own direction and an opposite kind of strain in every direction, at right angles to it.Such a strain is known as

• linear strain

• lateral strain (Ans)

• volumetric strain

• shear strain

34.The ratio of the lateral strain to the linear strain is called

• modulus of elasticity

• modulus of rigidity

• bulk modulus

• poisson’s ratio (Ans)

35.The poisson’s ratio for steel varies from

• 0.23 to 0.27 (Ans)

• 0.25 to 0.33

• 0.31 to 0.34

• 0.32 to 0.42

36.The poisson’s ratio for cast iron varies from

• 0.23 to 0.27

• 0.25 to 0.33 (Ans)

• 0.31 to 0.34

• 0.32 to 0.42

37.When a bar of length l, width b and thickness t is subjected to a pullof p, its

• length, width and thickness increases

• length, width and thickness decreases

• length increases, width and thickness decreases (Ans)

• length decreases, width and thickness increases

38.The ratio of change in volume to the original volume is called

• linear strain

• lateral strain

• volumetric strain (Ans)

• poisson’s ratio

39.When a bar of length l, width b and thickness t is subjected to a push of p, its

• length, width and thickness increases

• length, width and thickness decreases

• length increases, width and thickness decreases

• length decreases, width and thickness increases (Ans)

40.The volumetric strain is the ratio of the

• original thickness to the change in thickness

• change in thickness to the original thickness

• original volume to the change in volume

• change in volume to the original volume (Ans)

41.When a body is subjected to three mutually perpendicular stresses, of equal intensity, the ratio of direct stress to the corresponding volumetric strain is known as

• Young’s modulus

• modulus of rigidity

• bulk modulus (Ans)

• Poisson’s ratio

42.The relation between Young’s modulus (E) and bulk modulus (K) is given by

• K=3m-2/mE

• K=mE/3m-2

• K=3(m-2)/mE

• K=mE/3(m-2) (Ans)

43.The ratio of bulk modulus to Young’s modulus for a Poisson’s ratio of 0.25 will be

• 1/3

• 2/3 (Ans)

• 1

• 3/2

44.The relation between Young’s modulus (E), shear modulus (C) and bulk modulus (K) is given by

• E=3K.C/3K+C

• E=6K.C/3K+C

• E=9K.C/3K+C (Ans)

• E=12K.C/3K+C

45.The relation between modulus of elasticity (E) and modulus of rigidity (C) is given by

• C=mE/2(m+1) (Ans)

• C=2(m+1)/mE

• C=2mE/m+1

• C=m+1/2mE

46.The ratio of shear modulus to the modulus of elasticity for a Poisson’s ratio of 0.4 will be

• 5/7

• 7/5

• 5/14 (Ans)

• 14/5

47.If the modulus of elasticity for a given material is twice its modulus of rigidity, then bulk modulus is equal to

• 2C

• 3C

• 2C/3 (Ans)

• 3C/2

48.The Young’s modulus of a material is 125 Gpa and Poisson’s ratio is 0.25.The modulus of rigidity of the material is

• 30 Gpa

• 50 Gpa (Ans)

• 80 Gpa

• 100 Gpa

49.Within elastic limit, shear stress is…………….shear strain

• equal to

• less than

• directly proportional to (Ans)

• inversely proportional to

50.Shear modulus is the ratio of

• linear stress to linear strain

• linear stress to lateral strain

• volumetric strain to linear strain

• shear stress to shear strain (Ans)

51.A localized compressive stress at the area of contact between two members is known as

• tensile stress

• bending stress

• crushing stress (Ans)

• shear stress

52.The maximum diameter of the hole that can be punched from a plate of maximum shear stress 1/4th of its maximum crushing stress of punch, is equal to

• t

• 2t

• 4t (Ans)

• 8t

where t=thickness of the plate.

53.In the above question, the normal stress on an oblique section will be maximum, when θ is equal to

• 0o (Ans)

• 30o

• 45o

• 90o

54.When a body is subjected to a direct tensile stress (ϭ) in one plane, then maximum normal stress occurs at a section inclined at………..to the normal of the section

• 0o (Ans)

• 30o

• 45o

• 90o

55. When a body is subjected to a direct tensile stress (ϭ) in one plane, then maximum shear stress is…………………..the maximum normal stress

• equal to

• one-half (Ans)

• two-third

• twice

56.The maximum shear stress is………the algebraic difference of maximum and minimum normal stresses.

• equal to

• one-half (Ans)

• one-fourth

• twice

57. Mohr’s circle is used to determine the stresses on an oblique section of a body subjected to

• direct tensile stress in one plane accompanied by a shear stress

• direct tensile stress in two mutually perpendicular directions

• direct tensile stress in two mutually perpendicular directions accompanied by a simple shear stress

• all of the above (Ans)

58.The extremeties of any diameter on Mohr’s circle represent

• principle stresses

• normal stresses on planes at 45o (Ans)

• shear stresses on planes at 45o

• normal and shear stresses on plane

59.The energy stored in a body when strained within elastic limit is known as

• resilience

• proof resilience

• strain energy (Ans)

• impact energy

60.The total strain energy stored in a body is termed as

• resilience (Ans)

• proof resilience

• modulus of resilience

• impact energy

61.Strain energy is the

• energy stored in a body when strained within elastic limits (Ans)

• energy stored in a body when strained upto the breaking of a specimen

• maximum strain energy which can be stored in a body

• proof resilience per unit volume of a material

62.The strain energy stored in a body, when suddenly loaded, is………….the strain energy stored when same load is applied gradually.

• Equal to

• one-half

• twice

• four times (Ans)

63.Resilience is the

• energy stored in a body when strained within elastic limits (Ans)

• energy stored in a body when strained upto the breaking of a specimen

• maximum strain energy which can be stored in a body

• none of the above (Ans)

64.The stress induced in a body, when suddenly loaded, is………….the stress induced when the same load is applied gradually.

• Equal to

• one-half

• twice(Ans)

• four times

65.The strain energy stored in a spring, when subjected to maximum load, without suffering permanent distortion, is known as

• impact energy

• proof resilience (Ans)

• proof stress

• modulus of resilience

66.The capacity of a strained body for doing work on the removal of the straining force, is called

• strain energy

• resilience (Ans)

• impact energy

• proof resilience

67.A beam which is fixed at one end and free at the other is called

• simply supported beam

• fixed beam

• overhanging beam

• cantilever beam (Ans)

68.A beam extending beyond the supports is called

• simply supported beam

• fixed beam

• overhanging beam (Ans)

• cantilever beam

69.A beam encastered at both the ends is called

• simply supported beam

• fixed beam (Ans)

• continuous beam

• cantilever beam

70.A beam supported on more than two supports is called

• simply supported beam

• fixed beam

• overhanging beam (Ans)

• continuous beam

71.A cantilever beam is one which is

• fixed at both ends

• fixed at both ends and free at the other end (Ans)

• supported at its ends

• supported on more than two supports

72.A continuous beam is one which is

• fixed at both ends

• fixed at both ends and free at the other end

• extending beyond the supports

• supported on more than two supports (Ans)

73.A concentrated load is one which

• acts at a point on a beam (Ans)

• spreads non-uniformly over the whole length of beam

• spreads uniformly over the whole length of beam

• varies uniformly over the whole length of beam

74.The bending moment on a section is maximum where shear force is

• minimum

• maximum

• changing sign (Ans)

• zero

75.When a load on the free end of a cantilever beam is increased, failure will occur

• at the free end

• at the fixed end (Ans)

• in the middle of the beam

• at a distance 2l/3 from free end

76.The bending moment at the free end of a cantilever beam is

• zero (Ans)

• minimum

• maximum

77.The shear force of a cantilever beam of length l carrying a uniformly distributed load of w per unit length is…………… at the free end

• zero (Ans)

• wl/4

• wl/2

• wl

78.The shear force of a cantilever beam of length l carrying a uniformly distributed load of w per unit length is…………… at the fixed end

• zero

• wl/4

• wl/2

• wl (Ans)

79. The shear force diagram of a cantilever beam of length l and carrying a uniformly distributed load of w per unit length will be

• a right angled triangle (Ans)

• an issoscles triangle

• an equilateral triangle

• a rectangle

80.The bending moment of a cantilever beam of length l carrying a uniformly distributed load of w per unit length is…………… at the free end

• zero (Ans)

• wl/4

• wl/2

• wl

81.The shear force and bending moment are zero at the free end of a cantilever beam, if it carries a

• point load at the free end

• point load at the middle of its length

• uniformly distributed load over the whole length (Ans)

• none of the above

82.The bending moment of a cantilever beam of length l carrying a uniformly distributed load of w per unit length is…………… at the fixed end

• wl/4

• wl/2

• wl

• wl2/2 (Ans)

83.The shear force diagram for a cantilever beam of length l and carrying a gradually varying load from zero at free end and w per unit length at the fixed end is a

• horizontal straight line

• vertical straight line

• inclined line

• parabolic curve (Ans)

84.The shear force of a cantilever beam of length l and carrying a gradually varying load from zero at the free end and w per unit length at the fixed end is ………………..at the fixed end

• zero (Ans)

• wl/4

• wl/2 (Ans)

• wl

85.The bending moment of a cantilever beam of length l and carrying a gradually varying load from zero at the free end and w per unit length at the fixed end is ………………..at the fixed end

• wl/2

• wl

• wl2/2

• wl2/6 (Ans)

86.The maximum bending moment of a simply supported beam of span l and carrying a point load W at the centre of beam, is

• wl/4 (Ans)

• Wl/2

• Wl

• Wl2/4

87.The bending moment diagram for a simply supported beam loaded in its centre is

• a right angled triangle

• an issoscles triangle (Ans)

• an equilateral triangle

• a rectangle

88.The shear force diagram for a simply supported beam carrying a uniformly distributed load of w per unit length, consists of

• one right angled triangle

• two right angled triangles (Ans)

• one equilateral triangle

• two equilateral triangles

89.The bending moment diagram for a simply supported beam carrying a uniformly distributed load of w per unit length, will be

• a horizontal line

• a vertical line

• an inclined line

• a parabolic curve (Ans)

90.The shear force at the centre of a simply supported beam with a gradually varying load from zero at both ends to w per metre at the centre is wl/4

• zero (Ans)

• wl/4

• wl/2

• wl2/2

91.The point of contraflexure is a point where

• shear force changes sign

• bending moment changes sign (Ans)

• shear force is maximum

• bending moment is maximum

92.When shear force at a point is zero, then bending moment is…………….at that point

• zero

• minimum

• maximum (Ans)

• infinity

93.In a simply supported beam carrying a uniformly distributed load w per unit length, the point of contraflexure

• lies in the centre of the beam

• lies at the ends of the beam

• depends upon the length of beam

• does not exist

94.When there is a sudden increase or decrease in shear force diagram between any two points, it indicates that there is a

• point load at the two points (Ans)

• uniformly distributed load between the two points

• uniformly varying load between the two points

95.When the shear force diagram is a parabolic curve between two points, it indicates that there is a

• point load at the two points

• uniformly distributed load between the two points

• uniformly varying load between the two points (Ans)

96.In a beam where shear force changes sign, the bending moment will be

• zero

• minimum

• maximum (Ans)

• infinity

97.The point of contraflexure occurs in

• cantilever beams

• simply supported beams

• overhanging beams (Ans)

• fixded beams

98.The bending moment at a section tends to bend or deflect the beam and the internal stresses resist its bending.The resistance offered by the internal stresses, to the bending, is called

• compressive stress

• shear stress

• bending stress (Ans)

• elastic modulus

99.The assumption, generally, made in the theory of simple bending is that

• the beam material is perfectly homogeneous and isotropic

• the beam material is stressed within its elastic limit

• the plane sections before bending remain plane after bending

• all of the above (Ans)

100.In a simple bending theory, one of the assumption is that the material of the beam is isotropic.The assumptiom means that the

• normal stress remains constant in all dorections

• normal stress varies linearly in the material

• elastic constant are same in all the directions (Ans)

• elastic constant varies linearly in the material

101.In a simple bending of beams, the stress in the beam varies

• linearly (Ans)

• parabolically

• hyperbolically

• elliptically

102.In a simple bending theory, one of the assumption is that the plane sections before bending remain plane after bending. This assumption means that

• stress is uniform throughout the beam

• strain is uniform throughout the beam

• stress is proportional to the distance from the neutral axis

• strain is proportional to the distance from the neutral axis (Ans)

103.When a beam is subjected to a bending moment, the strain in a layer is …………. the distance from the neutral axis.

• Equal to

• directly proportional to (Ans)

• inversely proportional to

• independent of

104.The bending equation is

• M/I=Ϭ/y=E/R (Ans)

• T/J=τ/r=Cθ/l

• M/y= Ϭ/I=E/R

• T/r= τ/J=Cθ/l

105.A section of beam is said to be in pure bending, if it is subjected to

• constant bending moment and constant shear force

• constant shear force and zero bending moment

• constant bending moment and zero shear force (Ans)

• none of the above

106.When a beam is subjected to bending moment, the stress at any point is …………. the distance of the point from the neutral axis.

• Equal to

• directly proportional to (Ans)

• inversely proportional to

• independent of

107.The neutral axis of the cross-section a beam is that axis at which the bending stress is

• zero (Ans)

• minimum

• maximum

• infinity

108.The section modulus (Z) of a beam is given by

• I/y (Ans)

• I.y

• y/I

• M/I

109.The section modulus of a rectangular section about an axis through its C.G., is

• b/2

• d/2

• bd2/2

• bd2/6 (Ans)

110.The bending stress in a beam is ……………… section modulus.

• Directly proportional to

• inversely proportional to (Ans)

111.The section modulus of a circular section about an axis through its C.G., is

• πd2/4

• πd2/16

• πd3/16

• πd3/32 (Ans)

112.A square beam and a circular beam have the same length, same allowable stress and the same bending moment. The ratio of weight of the square beam to the circular beam is

• 1/2

• 1

• 1/1.12 (Ans)

• 1/2

113.For a given stress, the ratio of moment of resistance if a beam of square cross-section when placed with its two sides horizontal to the moment of resistance with its diagonal horizontal, is

• 1/2

• 1

• 1/2

• 2 (Ans)

114.Two beams, one of circular cross section and the other of square cross section, have equal areas of cross-sections. When these beams are subjected to bending,

• both beams are equally economical

• square beam is more economical (Ans)

• circular beam is more economical

• none of these

115.When a cantilever beam is loaded at its free end, the maximum compressive stress shall develop at

• bottom fibre (Ans)

• top fibre

• neutral axis

• centre of gravity

116.A beam of uniform strength may be obtained by

• keeping the width uniform and varying the depth

• keeping the depth uniform and varying the width

• varying the width and depth both

• any one of the above (Ans)

117.If the depth is kept constant for a beam of uniform strength, then its width will vary in proportional to

• M (Ans)

• M

• M2

• M3

Where M=Bending moment

118.A beam of uniform strength has

• same cross-section throughout the beam

• same bending stress at every section (Ans)

• same bending moment at every section

• same shear stress at every section

119.The bending stress in a beam is ……….. bending moment

• equal to

• less than

• more than

• directly proportional to (Ans)

120.At the neutral axis of a beam

• the layers are subjected to maximum bending stress

• the layers are subjected to minimum bending stress

• the layers are subjected to compression

• the layers do not undergo any strain ( Ans)

121.The neutral axis of a beam is subjected to ………… stress.

• Zero (Ans)

• maximum tensile

• minimum tensile

• maximum compressive

122.The neutral axis of a transverse section of a beam passes through the centre of gravity of the section and is

• in the vertical plane

• in the horizontal plane

• in the same plane in which the beam bends(Ans)

123.In a beam subjected to pure bending, the intensity of stress in any fibre is ……….. the distance of the fibre from the neutral axis

• equal to

• less than

• more than

• directly proportional (Ans)

124.The rectangular beam ‘A’ has length l, width b and depth d.Another beam ‘B’ has the same length and width but depth is double that of ‘A’. The elastic strength of beam B will be …………….. as compared to beam A.

• Same

• double

• four times (Ans)

• six times

125.The rectangular beam ‘A’ has length l, width b and depth d.Another beam ‘B’ has the same length and width but depth is double that of ‘A’. The elastic strength of beam B will be …………….. as compared to beam A.

• Same

• double (Ans)

• four times

• six times

126.The rectangular beam ‘A’ has length l, width b and depth d.Another beam ‘B’ has the same length and width but depth is double that of ‘A’. The elastic strength of beam B will be …………….. as compared to beam A.

• Same

• one-half (Ans)

• one-fourth

• one-eighth

127.When a rectangular beam is loaded transversely, the maximum tensile stress is developed on the

• top layer (Ans)

• bottom layer

• neutral axis

• every cross-section

128.When a rectangular beam is loaded transversely, the maximum compressive stress is developed on the

• top layer

• bottom layer (Ans)

• neutral axis

• every cross-section

129.At the neutral axis of a beam, the shear stress is

• zero

• minimum

• maximum (Ans)

• infinity

130.the maximum shear stress developed in a beam of rectangular section is …………. the average shear stress.

• Equal to

• 4/3 times

• 1.5 times (Ans)

• twice

131.The maximum shear stress developed in a beam of circular section is …………. the average shear stress.

• Equal to

• 4/3 times (Ans)

• 1.5 times

• twice

132.The ratio of maximum shear stress developed in a rectangular beam and a circular beam of the same cross-section area is

• 2/3

• 3/4

• 1

• 9/8 (Ans)

133.A beam of triangular section is placed with its base horizontal. The maximum shear stress occurs at

• apex of the triangle

• mid of the height (Ans)

• centre of gravity of the triangle

• base of the triangle

134.A base of T-section is subjected to a shear force of F. The maximum shear force will occur at the

• top of the section

• bottom of the section

• neutral axis of the section (Ans)

• junction of web and flange

135. A flitched beam is used to

• change the shape of the beam

• effect the saving in material

• equalize the strength in tension and compression (Ans)

• increase the cross-section of the beam

136.A rectangular beam of length l supported at its two ends carries a central point load W.The maximum deflection occurs

• at the ends

• at l/3 from both ends

• at the centre (Ans)

• none of these

137.The maximum deflection of a cantilever beam of length l with a point load W at the free end is

• Wl3/3EI (Ans)

• Wl3/8EI

• Wl3/16EI

• Wl3/48EI

138.The maximum deflection of a cantilever beam of length l with a uniformly distributed load of w per unit length is

• Wl3/3EI (Ans)

• Wl3/8EI

• Wl3/16EI

• Wl3/48EI

where W=wl

139. The maximum deflection of a fixed beam carrying a central point load lies at

• fixed ends

• centre of beam (Ans)

• l/3 from fixed ends

• none of these

140.The maximum deflection of a fixed beam of length l carrying a central point load W is

• Wl3/48EI

• Wl3/96EI

• Wl3/192EI (Ans)

• Wl3/384EI

141.The maximum deflection of a fixed beam of length l carrying a total load W uniformly distributed over the whole length is

• Wl3/48EI

• Wl3/96EI

• Wl3/192EI

• Wl3/384EI (Ans)

142.The product of the tangential force acting on the shaft and its distance from the axis of the shaft(i.e. Radius of shaft) is known as

• bending moment

• twisting moment (Ans)

• torsional rigidity

• flexural rigidity

143.When a shaft is subjected to a twisting moment, every cross-section of the shaft will be under

• tensile stress

• compressive stress

• shear stress (Ans)

• bending stress

144.The shear stress at the centre of a circular shaft under torsion is

• zero (Ans)

• minimum

• maximum

• infinity

145.The shear stress at the outermost fibres of a circular shaft under torsion is

• zero

• minimum

• maximum (Ans)

• infinity

146.The torsional rigidity of a shaft is given by

• T/J

• T/θ (Ans)

• T/r

• T/G

147.When a shaft is subjected to torsion, the shear stress induced in the shaft varies from

• minimum at the centre to maximum at the circumference

• maximum at the centre to maximum at the circumference

• zero at the centre to maximum at the circumference (Ans)

• maximum at the centre to zero at the circumference

148.For a shaft, the shear stress at a point is…………….the distance from the axis of the shaft

• equal to

• directly proportional to (Ans)

• inversely proportional to

149.The polar moment of inertia of a solid circular shaft if diameter(D) is

• πD3/16

• πD3/32

• πD4/32 (Ans)

• πD4/64

150.The polar moment of inertia of a follow shaft of outer diameter(D)

and inner diameter (d) is

• π/16(D3 – d3)

• π/16(D4 – d4) (Ans)

• π/16(D4 – d4) (Ans)

• π/16(D4 – d4)

151.Which of the following is the correct torsion equation?

• M/I=Ϭ/y=E/R

• T/J=τ/R=Cθ/l (Ans)

• M/R= T/J=Cθ/l

• T/l= τ/J=R/Cθ

152.The torque transmitted by a solid shaft of diameter(D) is

• π/4* τ*D3

• π/16* τ*D3

• π/32* τ*D3

• π/64* τ*D3

Where τ=Maximum allowable shear stress

153.Two solid shafts ‘A’ and ‘B’ are made of the same material.The shaft ‘A’ is of 50 mm diameter and shaft ‘B’ is of 100 mm diameter. The strength of shaft ‘B’ is……………as that of shaft A.

• One-half

• double

• four times

• eight times (Ans)

154.In the torsion equation T/J=τ/R=Cθ/l, the term J/R is called

• shear modulus

• section modulus

• polar modulus (Ans)

• none of these

155.The polar modulus for a solid shaft of diameter(D) is

• πD2/4

• πD3/16 (Ans)

• πD3/32

• πD4/64

156.The polar modulus for a follow shaft of outer diameter(D)

and inner diameter (d) is

• π/4(D2– d2/D)

• π/16(D3 – d3/D)

• π/16(D4 – d4/D) (Ans)

• π/32(D4 – d4/D)