### Multiple Choice Questions and Answers (MCQs) on Strength of Materials

01. According to Lami’s theorem

(A) Three forces acting at a point will be in equilibrium
(B) Three forces acting at a point can be represented by a triangle, each side being proportional to force
(C) If three forces acting upon a particle are represented in magnitude and direction by the sides of a triangle, taken in order, they will be in equilibrium
(D) If three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two

02. A number of forces acting at a point will be in equilibrium if

(A) Their total sum is zero
(B) Two resolved parts in two directions at right angles are equal
(C) Sum of resolved parts in any two perpendicular directions are both zero
(D) All of them are inclined equally

03. The center of gravity of a triangle lies at the point of

(A) Concurrence of the medians
(B) Intersection of its altitudes
(C) Intersection of bisector of angles
(D) Intersection of diagonals

04. Angle of friction is the

(A) Angle between normal reaction and the resultant of normal reaction and the limiting friction
(B) Ratio of limiting friction and normal reaction
(C) The ratio of minimum friction force to the friction force acting when the body is just about to move
(D) The ratio of minimum friction force to friction force acting when the body is in motion

05. Limiting force of friction is the

(A) Tangent of angle between normal reaction and the resultant of normal reaction and limiting friction
(B) Ratio of limiting friction and normal reaction
(C) The friction force acting when the body is just about to move
(D) The friction force acting when the body is in motion

06. The necessary condition for forces to be in equilibrium is that these should be

(A) Coplanar
(B) Meet at one point
(C) Both (A) and (B) above
(D) All be equal

07. Which of the following is the example of lever of first order?

(A) Arm of man
(B) Pair of scissors
(C) Pair of clinical tongs
(D) All of the above

08. A cable with a uniformly distributed load per horizontal metre run will take the following shape

(A) Straight line
(B) Parabola
(C) Hyperbola
(D) Elliptical

09. In determining stresses in frames by methods of sections, the frame is divided into two parts by an imaginary section drawn in such a way as not to cut more than

(A) Two members with unknown forces of the frame
(B) Three members with unknown forces of the frame
(C) Four members with unknown forces of the frame
(D) Three members with known forces of the frame

10. According to principle of transmissibility of forces, the effect of a force upon a body is

(A) Maximum when it acts at the center of gravity of a body
(B) Different at different points in its line of action
(C) The same at every point in its line of action
(D) Minimum when it acts at the C.G. of the body

11. Which of the following do not have identical dimensions?

(A) Momentum and impulse
(B) Torque and energy
(C) Torque and work
(D) Moment of a force and angular momentum

12. If a number of forces act simultaneously on a particle, it is possible

(A) Not a replace them by a single force
(B) To replace them by a single force
(C) To replace them by a single force through C.G.
(D) To replace them by a couple

13. Two coplanar couples having equal and opposite moments

(A) Balance each other
(B) Produce a couple and an unbalanced force
(C) Are equivalent
(D) Produce a moment of couple

14. If a suspended body is struck at the centre of percussion, then the pressure on die axis passing through the point of suspension will be

(A) Maximum
(B) Minimum
(C) Zero
(D) Infinity

15. Kinetic friction is the

(A) Tangent of angle between normal reaction and the resultant of normal reaction and the limiting friction
(B) Ratio of limiting friction and normal reaction
(C) The friction force acting when the body is just about to move
(D) The friction force acting when the body is in motion

16. The center of gravity of a uniform lamina lies at

(A) The center of heavy portion
(B) The bottom surface
(C) The midpoint of its axis
(D) All of the above

17. The maximum twisting moment a shaft can resist, is the product of the permissible shear stress and

(A) Moment of inertia
(B) Polar moment of inertia
(C) Polar modulus
(D) Modulus of rigidly

18. The bending moment at E for the structure shown in below figure, is

(A) Zero
(B) 10 Tm
(C) 20 Tm
(D) 40 Tm

19. The deflection of any rectangular beam simply supported, is

(A) Directly proportional to its weight
(B) Inversely proportional to its width
(C) Inversely proportional to the cube of its depth
(D) Directly proportional to the cube of its length

20. Pick up the correct statement from the following:

(A) The point through which the resultant of the shear stresses passes is known as shear centre
(B) In the standard rolled channels, the shear centre is on the horizontal line passing through and away from the C.G. beyond web (C) In equal angles, the shear centre is on the horizontal plane and away from the C.G., outside of the leg projection
(D) All the above

21. A heavy string attached at two ends at same horizontal level and when central dip is very small approaches the following curve

(A) Catenary
(B) Parabola
(C) Hyperbola
(D) Elliptical

22. A beam is said to be of uniform strength, if

(A) B.M. is same throughout the beam
(B) Deflection is same throughout the beam
(C) Bending stress is same throughout the beam
(D) Shear stress is same throughout the beam

23. Pick up the correct statement from the following:

(A) The distance of the eccentric axial load from the C.G. beyond which tension develops, is known as kern distance
(B) In visco-elastic material, stress-strain relation is dependent on time
(C) An orthotropic material has different properties in three mutually perpendicular directions
(D) All the above

24. The ratio of limiting friction and normal reaction is known as

(A) Coefficient of friction
(B) Angle of friction
(C) Angle of repose
(D) Sliding friction

25. If a three hinged parabolic arch carries a uniformly distributed load on its entire span, every section of the arch resists.

(A) Compressive force
(B) Tensile force
(C) Shear force
(D) Bending moment

26. The under mentioned type is simple strain

(A) Tensile strain
(B) Compressive strain
(C) Shear strain
(D) All the above

27. If rain is falling in the opposite direction of the movement of a pedestrian, he has to hold his umbrella

(A) More inclined when moving
(B) Less inclined when moving
(C) More inclined when standing
(D) Less inclined when standing

28. The reaction at support A of the beam shown in below figure, is

(A) Zero
(B) 5 T
(C) 10 T
(D) 1 T

29. In a solid arch, shear force acts

(A) Vertically upwards
(B) Along the axis of the arch
(C) Perpendicular to the axis of arch
(D) Tangentially to the arch

30. The maximum frictional force which comes into play when a body just begins to slide over another surface is called

(A) Limiting friction
B) Sliding friction
(C) Rolling friction
(D) Kinematic friction

31. An arch with three hinges, is a structure

(A) Statically determinate
(B) Statically indeterminate
(C) Geometrically unstable
(D) Structurally sound but indeterminate

32. Beams of uniform strength are preferred to those of uniform section because these are economical for

(A) Large spans
(B) Heavy weights
(C) Light weights
(D) Short spans

33. The M.I. of hollow circular section about a central axis perpendicular to section as compared to its M.I. about horizontal axis is

(A) Same
(B) Double
(C) Half
(D) Four times

34. The tensile force required to cause an elongation of 0.045 mm in a steel rod of 1000 mm length and 12 mm diameter, is (where E = 2 × 106 kg/cm2)

(A) 166 kg|
(B) 102 kg
(C) 204 kg
(D) 74 kg

35. A long vertical member, subjected to an axial compressive load, is called

(A) A column
(B) A strut
(C) A tie
(D) A stanchion

36. In ideal machines

(A) Mechanical advantage is greater than velocity ratio
(B) Mechanical advantage is equal to velocity ratio
(C) Mechanical advantage is less than velocity ratio

37. The nature of the stress in horizontal members of the truss shown in below figure may be

(A) Compressive
(B) Tensile
(C) Shear
(D) Zero

38. The property of a material by which it can be drawn to a smaller section, due to tension, is called

(A) Plasticity
(B) Ductility
(C) Elasticity
(D) Malleability

39. The unit of force in S.I. units is

(A) Kilogram
(B) Newton
(C) Watt
(D) Dyne

40. A bending moment may be defined as:

(A) Arithmetic sum of the moments of all the forces on either side of the section
(B) Arithmetic sum of the forces on either side of the section
(C) Algebraic sum of the moments of all the forces on either side of the section
(D) None of these

41. If a circular beam of diameter d experiences a longitudinal strain P/E and a lateral strain 2P/mE, the volumetric strain is

(A) (P/E) + (2P/mE)
(B) (P/E) – (2P/mE)
(C) (P/E) + (mE/2P)
(D) (P/E) – (mE/2P)

42. The resolved part of the resultant of two forces inclined at an angle ϕ in a given direction is equal to

(A) The algebraic sum of the resolved parts of the forces in the given direction
(B) The sum of the resolved parts of the forces in the given direction (C) The difference of the forces multiplied by the cosine of ϕ
(D) The sum of the forces multiplied by the sine of ϕ

43. For structural analysis, Maxwell’s reciprocal theorem can be applied to:

(A) Plastic structures
(B) Elastic structures
(C) Symmetrical structures
(D) All the above

44. If all the dimensions of a bar are increased in the proportion n : 1, the proportion with which the maximum stress produced in the prismatic bar by its own weight, will increase in the ratio

(A) 1 : n
(B) n : 1
(C) 1 : (1/n)
(D) 1 : √n

45. Which of the following is a vector quantity?

(A) Energy
(B) Mass
(C) Momentum
(D) Angle

46. Pick up the incorrect statement

(A) The cross-sectional area of the welded member is effective
(B) A welded joint develops strength of its parent metal
(C) Welded joints provide rigidity
(D) Welding takes more time than riveting

47. A 8 metre long simply supported rectangular beam which carries a distributed load 45 kg/m. experiences a maximum fibre stress 160 kg/cm2. If the moment of inertia of the beam is 640 cm4, the overall depth of the beam is

(A) 10 cm
(B) 12 cm
(C) 15 cm
(D) 18 cm

48. A heavy ladder resting on floor and against a vertical wall may not be in equilibrium, if

(A) The floor is smooth, the wall is rough
(B) The floor is rough, the wall is smooth
(C) The floor and wall both are smooth surfaces
(D) The floor and wall both are rough surfaces

49. A triangular section having base b, height h, is placed with its base horizontal. If the shear stress at a depth y from top is q, the maximum shear stress is

(A) 3S/bh
(B) 4S/bh
(C) 4b/Sh
(D) 3b/bS