MCQs on Analysis of Truss Structures

NOTE: Statically determinate-- Perfect Truss

Statically Indeterminate-- Imperfect Truss

1. The number of independent equations to be satisfied for static equilibrium of a plane structure is

a) 1
b) 2
c) 3
d) 6
Ans: c

2. If there are m unknown member forces, r unknown reaction components and j number of joints, then the degree of static indeterminacy of a pin-jointed plane frame is given by
a) m + r + 2j
b) m - r + 2j
c) m + r - 2j
d) m + r - 3j
Ans: c




3. Number of unknown internal forces in each member of a rigid jointed plane frame is
a) 1
b) 2
c) 3
d) 6
Ans: b

4. Degree of static indeterminacy of a rigid-jointed plane frame having 15 members, 3 reaction components and 14 joints is
a) 2
b) 3
c) 6
d) 8
Ans: c

5. A pin-jointed plane frame is unstable if
a) (m + r)<2j
b) m + r = 2j
c) (m + r)>2j
d) none of the above
where m is the number of members, r is reaction components and j is a number of joints
Ans: a

6. A rigid-jointed plane frame is stable and statically determinate if
a) (m + r) = 2j
b) (m + r) = 3j
c) (3m + r) = 3j
d) (m + 3r) = 3j
where m is number of members, r is reaction components and j is number of joints
Ans: c

7. The number of independent equations to be satisfied for static equilibrium in a space structure is
a) 2
b) 3
c) 4
d) 6
Ans: b

8. The number of independent displacement components at each joint of a rigid-jointed space frame is
a) 1
b) 2
c) 3
d) 6
Ans: d

9. The principle of virtual work can be applied to elastic system by considering the virtual work of
a) internal forces only
b) external forces only
c) internal as well as external forces
d) none of the above
Ans: c

10. The unit of force in S.I. units is
(a) kilogram
(b) newton
(c) watt
(d) dyne
(e) joule.
Ans: b

11. The unit of work or energy in S.I. units is
(a) newton
(b) pascal
(c) kilogram meter
(d) watt
(e) joule.
Ans: e

12. The unit of power in S.I. units is
(a) newton meter
(b) watt
(c) joule
(d) kilogram meter/sec.
(e) pascal per sec.
Ans: b

13. Forces are called concurrent when their lines of action meet in
(a) one point
(b) two points
(c) plane
(d) perpendicular planes
(e) different planes.
Ans: a

14. Forces are called coplanar when all of them acting on body lie in
(a) one point
(b) one plane
(c) different planes
(d) perpendicular planes
(e) different points.
Ans: b

15. A force acting on a body may
(a) introduce internal stresses
(b) balance the other forces acting on it
(c) retard its motion
(d) change its motion
(e) all of the above.
Ans: e

16. Which is the correct statement about the law of polygon forces?
(a) if any number of forces acting at a point can be represented by the sides
of a polygon taken in order, then the forces are in equilibrium
(b) if any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon, then
the forces are in equilibrium
(c) if a polygon representing forces acting at a point is closed then forces are in equilibrium
(d) if any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon taken in
order, then the forces are in equilibrium
(e) none of the above.
Ans: d

17. Effect of a force on a body depends upon
(a) magnitude
(b) direction
(c) position or line of action
(d) all of the above
(e) none of the above.
Ans: d

18. 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 with a single force
(c) to replace them with a single force through C.G.
(d) to replace them with a couple
(e) to replace them with a couple and a force.
Ans: b

19. A force is completely defined when we specify
(a) magnitude
(b) direction
(c) point of application
(d) all of the above
(e) none of the above.
Ans: d

20. If two equal forces of magnitude P act at an angle 9°, their results will be
(a) P/2 cos 9/2
(b) IP sin 9/2
(c) 2P tan 9/2
(d) IP cos 9/2
(e) P.sin 9/2.
Ans: d

21. The algebraic sum of the resolved parts of a number of forces in a given direction is equal to the resolved part of their
resultant in the same direction. This is as per the principle of
(a) forces
(b) independence of forces
(c) dependence of forces
(d) the balance of force
(e) resolution of forces.
Ans: e

22. The resolved part of the resultant of two forces inclined at an angle 9 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 9
(d) the sum of the forces multiplied by the sine of 9
(e) the sum of the forces multiplied by the tangent of 9.
Ans: a

23. Which of the following do not have identical dimensions?
(a) Momentum and impulse
(b) Torque and energy
(c) Torque and work
(d) Kinetic energy and potential energy
(e) Moment of a force and angular momentum.
Ans: e

24. Which of the following is not the unit of distance?
(a) angstrom
(b) light year
(c) micron
(d) millimetre
(e) milestone.
Ans: e

25. Which of the following is not the unit of power?
(a) kW (kilowatt)
(b) hp (horsepower)
(c) kcal/sec
(d) kg m/sec
(e) kcal/kg-sec.
Ans: e

26. Which of the following is not the unit of work, energy and heat ?
(a) kcal
(b) kg m
(c) kWhr
(d) hp
(e) hp-hr.
Ans: d

27. Which of the following is not the unit of pressure?
(a) kg/cm
(b) ata
(c) atmosphere
(d) mm of wcl
(e) newton.
Ans: e

28. The weight of a body is due to
(a) the centripetal force of the earth
(b) gravitational pull exerted by the earth
(c) forces experienced by the body in the atmosphere
(d) the force of attraction experienced by particles
(e) the gravitational force of attraction towards the centre of the earth.
Ans: e

29. The forces, which meet at one point, but their lines of action do not lie in a plane, are called
(a) coplanar non-concurrent forces
(b) non-coplanar concurrent forces
(c) non-coplanar non-concurrent forces
(d) intersecting forces
(e) none of the above.
Ans: b

30. When trying to turn a key into a lock, following is applied
(a) coplanar force
(b) non-coplanar forces
(c) lever
(d) moment
(e) couple.
Ans: e

31. Which of the following is not a scalar quantity
(a) time
(b) mass
(c) volume
(d) density
(e) acceleration.
Ans: e

32. According to principle of transmissibility of forces, the effect of a force upon a body is
(a) maximum when it acts at the centre 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
(e) none of the above.
Ans: c

33. Which of the following is a vector quantity
(a) energy
(b) mass
(c) momentum
(d) angle
(e) speed.
Ans: c

34. The magnitude of two forces, which when acting at right angle produce resultant force of VlOkg and when acting at 60°
produce resultant of Vl3 kg. These forces are
(a) 2 and V6
(b) 3 and 1 kg
(c) V5andV5
(d) 2 and 5
(e) none of the above.
Ans: c

35. 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) the sum of resolved parts in any two perpendicular directions are both zero
(d) all of them are inclined equally
(e) none of the above.
Ans: c

28. Two non-collinear parallel equal forces acting in opposite direction
(a) balance each other
(b) constitute a moment
(c) constitute a couple
(d) constitute a moment of couple
(e) constitute a resultant couple.
Ans: c

29. According to principle of moments
(a) if a system of coplanar forces is in equilibrium, then their algebraic sum is zero
(b) if a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is
zero
(c) the algebraic sum of the moments of any two forces about any point is equal to the moment of the resultant about the same
point
(d) positive and negative couples can be balanced
(e) none of the above.
Ans: b

30. Which of the following is not a vector quantity
(a) weight
(b) velocity
(c) acceleration
(d) force
(e) moment.
Ans: a

31. According to law of triangle of forces
(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 the force
(c) if three forces acting upon a particles 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
(e) none of the above.
Ans: c

32. If a rigid body is in equilibrium under the action of three forces, then
(a) these forces are equal
(b) the lines of action of these forces meet in a point
(c) the lines of action of these forces are parallel
(d) (b) and (c) above
(e) none of the above.
Ans: d

33. D' Alembert's principle is used for
(a) reducing the problem of kinetics to equivalent statics problem
(b) determining stresses in the truss
(c) stability of floating bodies
(d) designing safe structures
(e) solving kinematic problems.
Ans: a

34. 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
(e) will be in equilibrium under all conditions.
Ans: c

35. 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 the 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
(e) none of the above.
Ans: d

36. 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 the couple
(e) can not balance each other.
Ans: e

37. A framed structure is perfect if it contains members equal to
(a) 2n-3
(b) n-l
(c) '2n-l
(d) n - 2
(e) 3n-2.
where n = number of joints in a frame
Ans: a

39. The product of either force of couple with the arm of the couple is called
(a) resultant couple
(b) moment of the forces
(c) resulting couple
(d) moment of the couple
(e) none of the above.
Ans: d

40. 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
(e) four members with two known forces.
Ans: b

41. The centre of gravity of a uniform lamina lies at
(a) the centre of the heavy portion
(b) the bottom surface
(c) the midpoint of its axis
(d) all of the above
(e) none of the above.
Ans: c

42. Center of gravity of a solid cone lies on the axis at the height
(a) one-fourth of the total height above the base
(b) one-third of the total height above the base
(c) one-half of the total height ab the ve base
(d) three-eighth of the total height above the base
(e) none of the above.
Ans: a

43. Center of percussion is
(a) the point of C.G.
(b) the point of metacentre
(c) the point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis
(d) point of suspension
(e) the point in a body about which it can rotate horizontally and oscillate under the influence of gravity.
Ans: c

44. Center of gravity of a thin hollow cone lies on the axis at a height of
(a) one-fourth of the total height above base
(b) one-third of the total height above base
(c) one-half of the total height above base
(d) three-eighth of the total height above the base
(e) none of the above.
Ans: b

45. The units of moment of inertia of an area are
(a) kg m2
(b) m4
(c) kg/m2
(d) m3
(e) kg/m4.
Ans: b

46. The centre of percussion of the homogeneous rod of length L suspended at the top will be
(a) L/2
(b) L/3
(c) 3L/4
(d) 2L/3
(e) 3L/8.
Ans: d

47. Which axial force is determined while analyzing a truss?
A. compressive force
B. tensile force
C. both a. and b.
D. none of the above

Ans: C

48. If a body is subjected to plastic impact, _______
A. only kinetic energy is conserved
B. only momentum is conserved
C. both a. and b.
D. none of the above

Ans: B

Note: - Some Questions are from the Core Mechanical, You can study as per your syllabus.

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