DESIGNING OF MATERIALS FOR STRENGTH:

Motion under gravity:

1.Curvilinear translation: In this the particles of a body move along parallel

circular arcs or curved paths.

Springs:

Displacement of loaded spring: let S =stiffness of the spring which is defined

as force required to cause one unit extension. y = displacement of the spring

under a load W. and the acceleration = a. Hence, the relation a =S.g.y/ W. =

constant x y. Frequency of free vibration = f = 1/2 π (√ Sg/W). And period

of vibration T = 1/f =1/2 π √ W/Sg.

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OBJECTIVE QUESTIONS:

1. During a tensile test on a specimen of 1 cm2 cross section, maximum

load observed was 8 tonnes and area of cross section at neck was .5 cm2.

Ultimate tensile strength of specimen is …….. ????

2. Materials obey’s Hooke’s law up to ……….. Elastic limit.

3. After reaching the yielding stage while testing a mild steel specimen,

strain……. Increases without increase in load.

4. True stress-strain curve for materials is plotted between …… load

/instantaneous cross-sectional area and loge (original

area/instantaneous area).

5. Strain energy per unit volume due to principle stress σ1, σ2, σ3 is………

????(6)

6. A cube subjected to three mutually perpendicular stress of equal intensity

p expresses a volumetric strain……. 3p/E (1-2/m).

7. Impact strength of a material is an index of it’s …… toughness.

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8. Volumetric strain for a rectangular specimen of length l, breadth b and

thickness t subjected to a pull of P is given by………e (l-2/m).

9. A hollow shaft of same cross section area as solid shaft transmits………

more torque.

10. The intensity of stress which causes unit strain is called……. Modulus of

elasticity.

11. in a block subjected to normal stresses σx and σy and shear stress τ along

two mutually perpendicular planes, the normal stress on plane making

angle θ with σx is given by…………… σx sin2 θ + σy sin2 θ + τ sin2t .

12. a composite bar made up of steel and copper bars of equal lengths are

heated through 100 C. the stresses developed shall be ……….

Compressive in both the materials.

13. Within elastic limit, stress is ……. Directly proportional to strain.

14. Modulus of rigidity is defined as the ratio of ……. Shear stress to shear

strain.

15. The shape of cantilever for uniformly distributed load will be …….

Parabolic.

16. The ultimate tensile stress of mild steel compared to ultimate

compressive stress is…… more.

17. Deflection of the centre of simply supported beam of length l carrying a

uniformly distributed load w kg/m will be ……… 5 w l4/384 EI.

18. Percentage reduction of area in performing tensile test on cast iron may

be of the order of ……..20%.

19. Poisons ratio is the ratio of …… lateral strain to longitudinal strain.

20. A coil is cut into two halves, the stiffness of cut coils will be……..

Double.

21. Elasticity of a M.S. specimen is defined by……… plastic flow.

22. in a uniform bar supported at one end in position, the maximum stress

under self weight of bar shall occur at the ………. Supported end.

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23. The extension of a uniformly tapering bar from diameter D2 at top to

diameter D1 at bottom and having length l, under an axial load P is given

by….. 4Pl/ πED1D2 .

24. When both ends of a column are fixed, the effective length is …….. Half

its length. ***

25. Slenderness of a column is zero when…….. Length is twice the radius

of gyration.

26. Formula adopted for IS codes are based on …….. Secant formula.

27. ratio of maximum deflection of a simply supported beam of span L

carrying (i) a concentrated load w at mid point and (ii) total load w1

uniformly distributed over the entire span, is…….. 16:1.

28. deflection at the mid span of a rectangular point beam under a

concentrated load acting there shall become……… if the length, width

and depth of beam are all doubled……. Half.???/

29. principal planes are planes having ………. Maximum shear stress.

30. for a cantilever of span L carrying a moment M at free end, deflection at

free end is…Ml3/2EI .

31. length of a column having Euler’s crippling load and Rankin’s crippling

load of same magnitude, is given by……….. √ πEr2/ (π2Ea –fa) . r

=minimum radius of gyration, E =young’s Modulus of Elasticity, a =

Rankine’s constant. the force acting along the circumference will cause

stress in the walls in a direction normal to the longitudinal axis of

cylinder, this stress is called…. Hoop stress.

32. a cantilever of length L and flexural rigidity EI, loaded with a central

point load W shall have a maximum deflection of ……. WL3/187 EI .

33. a boiler shell of 200 cm diameter and plate thickness 1.5 cm is subjected

to internal pressure of 1.5 MN/m2 , then the hoop stress will be ……….

100 MN/m2 .

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34. in a cantilever , maximum deflection occurs where……… bending

moment iszero.

35. Euler’s crippling load formula is valid for a columns having slenderness

ratio (in terms of effective length and minimum radius of gyration.)

…….. above 80 only.

36. the equation of elastic curve in terms of bending moment Mx at any

section is ……….. Ed2x/dx2 = -Mx/I.

37. A beam encastered at both the ends is known as……… a fixed beam.

38. At the principle planes ……… normal stress is maximum or minimum

and the shear stress is zero.

39. Relationship between modulus of elasticity E, modulus of rigidity G

is……… G = E /2(1 +µ).

40. Torsional rigidity of a solid shaft of diameter d is proportional to

……….d4 .

41. The resistance offered by internal stress to bending to known

as…………. Moment of resistance.

42. A cylindrical section having no joint is known as …….. seamless section.

43. Bending stress at any section in a beam is …… directly proportional to

section modulus.

44. The Rankin’s crippling load is given by….. PR = fc A/ 1 + (l/r)2 .

45. a sudden change in shear force diagram between two points indicates that

there is …….. Point load at both the points.

46. if b is the width of a plate joined by diamond riveting of diameter d, the

efficiency of the joint is given by…….. (b – d)/ b.

47. Effective length of a column of length L fixed at one end and hinged at

the other end is …… L/√2

48. in a rectangular beam , when width, depth and length are doubled, the

bending stress……. Shall be halved.

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49. Slope and deflection at a point in a loaded cantilever beam carrying

several loads can be found out by the …… Macaulay’s method.

50. a composite bar made of steel and copper is heated up. The stresses

developed in steel and copper will be ….. Tensile and compressive.????

51. Diagram showing the variation of axial load along the span is……..

Normal thrust diagram.

52. The factor of safety considered in Euler’s formula for crippling load is -

1.

53. Rankin’s crippling load formula is valid for - For all columns.

54. Hoop stress in a thin cylinder of diameter d and thickness t subjected to

pressure p will be - pd/2t.

55. In I-section, the bending moment is resisted by - Web only.

56. A simply supported beam of span l carrying a uniformly varying load

from zero at one end to w at the other end undergoes a maximum bending

of - 8w l2/125.

57. Deflection at free end of a cantilever of span l and carrying a

concentrated load W, at distance l1 from the fixed end is - Wl12 (3l-l1) /

6EI .

58. The rate of change of shear force at any section is equal to - intensity of

loading.

59. The section modulus of a circular section about an axis through its c.g. is

- Πd3/32.

60. If the depth of a rectangular beam is halved, then the deflection for a

beam carrying a mid point load shall be - Doubled.

61. The depth to breadth ratio for the strongest rectangular beam that can be

cut out of a cylindrical wooden log is - √ 2: 1.

62. Beams of uniform strength are better as compared to beams of uniform

cross section as they are economical - for large spans.

63. A point of contraflecture occurs in a - Fixed beams.

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64. Shape of bending moment diagram for a simply supported beam carrying

a number of concentrated loads is a - Series of straight lines.

65. Shear force diagram for a cantilever beam carrying a uniformly

distributed load over its length is a - Triangle.

66. Minimum thickness of a flange at the end of shaft is determined by - The

fact that it must be sufficient to prevent the shaft from shearing out of the

flange on the cylindrical surface.

67. Shear stress in a rectangular beam exhibits a - parabolic variation.

68. Deflection at mid point of a simply supported beam carrying a u.d.l. w/m

run is - 5w l4/ 384EI.

69. In T-section - Most of the shear is resisted by the web only.

70. Mohr’s circle can be used to determine following stress on inclined

surface -Tangential stress.

71. A structure made up of several bars, joined together is known as - Frame.

72. For a beam of uniform strength, keeping depth constant, width varies in

proportion to - M.

73. If the width (b) and depth (d) of a simply supported beam are

interchanged, the mid point deflection shall change in the ratio of -

d3/b3.

74. A riveted joint in which the spacing of the rivets is staggered in such a

way that every rivet is in the middle of the two rivets of the opposite

row, is known as -Zig-zag riveted joint.

75. Section modulus Z is expressed as……. I / y.

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% & + < = > ± µ ¼ ½ ¾ Π Σ η α λ μ

ν ξ π ρ σ τ υ Ώ ≤ ≥ √ ∞ ← ↑

→ θ ↓ ∂ ∆ ≈ ≠ β γ δ

ε ζ Ф ω

WHY DO YOU LIKE YOUR SCHOOL?

I study in kendriya vidyalaya which is situated in Ojhar, Nasik. Our school

building is a tall building and consists of several rooms. All class rooms are

well furnished. There is a small garden and a play ground in our school. Our

teachers are very sympathetic to us and keep our interests in mind. All teachers

pay attention to every child of our class. Besides teaching a variety of

programmes are organized in our school. Our school has also own prizes in

several cultural programmes and games. For the above reason I like my school

best.

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