Engineering Mechanics MCQs
1. What is the unit of force in the International System of Units (SI)?
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a) Newton
b) Joule
c) Pascal
d) Watt
**Answer:** a) Newton
2. Which of the following is a scalar quantity?
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a) Force
b) Velocity
c) Mass
d) Acceleration
**Answer:** c) Mass
3. The moment of inertia of a rectangular section about its centroidal axis is given by which formula?
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a) \( \frac{bh^3}{12} \)
b) \( \frac{b^3h}{12} \)
c) \( \frac{b^2h}{12} \)
d) \( \frac{bh^2}{12} \)
**Answer:** a) \( \frac{bh^3}{12} \)
4. The angle between the resultant and the horizontal is called:
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a) Angle of incidence
b) Angle of deviation
c) Angle of repose
d) Angle of inclination
**Answer:** d) Angle of inclination
5. A force is completely specified when we know:
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a) Its magnitude
b) Its direction
c) Its point of application
d) All of the above
**Answer:** d) All of the above
6. The coefficient of restitution is a measure of:
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a) Elasticity
b) Friction
c) Viscosity
d) Shear strength
**Answer:** a) Elasticity
7. A body in equilibrium can have:
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a) Zero velocity
b) Uniform velocity
c) Variable velocity
d) Both a and b
**Answer:** d) Both a and b
8. The center of gravity of a solid hemisphere lies on the central radius at a distance of:
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a) \( \frac{3R}{8} \)
b) \( \frac{5R}{8} \)
c) \( \frac{R}{2} \)
d) \( \frac{R}{3} \)
**Answer:** b) \( \frac{5R}{8} \)
9. If a body is in equilibrium under the action of three forces, they must be:
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a) Concurrent
b) Parallel
c) Coplanar
d) Both a and c
**Answer:** d) Both a and c
10. The moment of a force about a point is the product of:
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a) Force and the perpendicular distance from the point to the line of action of the force
b) Mass and acceleration
c) Force and displacement
d) Velocity and time
**Answer:** a) Force and the perpendicular distance from the point to the line of action of the force
11. In a frictionless environment, the mechanical advantage of an ideal machine is:
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a) Less than 1
b) Equal to 1
c) Greater than 1
d) Infinity
**Answer:** c) Greater than 1
12. A force that tends to cause rotation about a point is known as:
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a) Moment
b) Torque
c) Couple
d) Centripetal force
**Answer:** b) Torque
13. In simple harmonic motion, the acceleration is:
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a) Constant
b) Zero
c) Proportional to displacement
d) Independent of displacement
**Answer:** c) Proportional to displacement
14. The product of mass and velocity is known as:
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a) Force
b) Momentum
c) Impulse
d) Work
**Answer:** b) Momentum
15. Which law states that every action has an equal and opposite reaction?
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a) Newton’s First Law
b) Newton’s Second Law
c) Newton’s Third Law
d) Law of Gravitation
**Answer:** c) Newton’s Third Law
16. The friction experienced by a body when it is at rest is called:
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a) Dynamic friction
b) Kinetic friction
c) Static friction
d) Rolling friction
**Answer:** c) Static friction
17. The efficiency of a machine is defined as:
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a) Work output divided by work input
b) Work input divided by work output
c) Force output divided by force input
d) Force input divided by force output
**Answer:** a) Work output divided by work input
18. The principle of transmissibility of forces states that:
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a) Forces can be moved anywhere in space
b) The effect of a force is unchanged if it is applied anywhere along its line of action
c) Forces can be resolved into components
d) None of the above
**Answer:** b) The effect of a force is unchanged if it is applied anywhere along its line of action
19. The impulse of a force is equal to the change in:
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a) Velocity
b) Acceleration
c) Momentum
d) Displacement
**Answer:** c) Momentum
20. The moment of inertia of a thin rod of length
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L about an axis through its center and perpendicular to its length is:
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a) \( \frac{ML^2}{12} \)
b) \( \frac{ML^2}{3} \)
c) \( \frac{ML^2}{2} \)
d) \( \frac{ML^2}{6} \)
**Answer:** a) \( \frac{ML^2}{12} \)
21. If a body is moving in a circular path with a constant speed, its acceleration is:
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a) Zero
b) Constant
c) Directed towards the center
d) Directed away from the center
**Answer:** c) Directed towards the center
22. The force required to keep a body moving in a circular path is called:
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a) Centrifugal force
b) Centripetal force
c) Gravitational force
d) Magnetic force
**Answer:** b) Centripetal force
23. When the net force acting on a body is zero, the body is said to be in:
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a) Dynamic equilibrium
b) Static equilibrium
c) Rotational equilibrium
d) Translational equilibrium
**Answer:** b) Static equilibrium
24. The point of application of the resultant of all the gravitational forces on a body is called its:
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a) Center of gravity
b) Center of mass
c) Centroid
d) Center of pressure
**Answer:** a) Center of gravity
25. The unit of work in the SI system is:
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a) Joule
b) Newton
c) Watt
d) Pascal
**Answer:** a) Joule
26. The tendency of a material to return to its original shape after deformation is called:
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a) Elasticity
b) Plasticity
c) Viscosity
d) Ductility
**Answer:** a) Elasticity
27. The force that opposes the relative motion between two surfaces in contact is called:
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a) Gravity
b) Friction
c) Tension
d) Compression
**Answer:** b) Friction
28. The force required to maintain a body in uniform circular motion is called:
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a) Centrifugal force
b) Centripetal force
c) Gravitational force
d) Inertial force
**Answer:** b) Centripetal force
29. When a body moves in a straight line, the work done by the force is:
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a) The product of force and displacement
b) The product of force and time
c) The product of force and velocity
d) The product of force and mass
**Answer:** a) The product of force and displacement
30. The law of conservation of energy states that:
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a) Energy cannot be created or destroyed
b) Energy can be created but not destroyed
c) Energy can be destroyed but not created
d) None of the above
**Answer:** a) Energy cannot be created or destroyed
31. The product of the moment of inertia and angular acceleration gives:
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a) Torque
b) Force
c) Work
d) Power
**Answer:** a) Torque
32. The distance between the point of application of a force and the axis of rotation is called:
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a) Moment arm
b) Torque
c) Leverage
d) Radius
**Answer:** a) Moment arm
33. The energy possessed by a body by virtue of its motion is called:
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a) Potential energy
b) Kinetic energy
c) Mechanical energy
d) Thermal energy
**Answer:** b) Kinetic energy
34. The moment of inertia of a body depends on:
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a) Mass of the body
b) Distribution of mass about the axis of rotation
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Sure! Here are additional MCQs on Engineering Mechanics:
51. In a simply supported beam, the reactions at the supports are:
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a) Vertical forces
b) Horizontal forces
c) Moments
d) Both vertical forces and moments
**Answer:** a) Vertical forces
52. The shear force in a beam is defined as:
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a) The force perpendicular to the longitudinal axis of the beam
b) The force parallel to the longitudinal axis of the beam
c) The moment of the forces about the longitudinal axis
d) The tension in the beam
**Answer:** a) The force perpendicular to the longitudinal axis of the beam
53. The bending moment in a beam is the result of:
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a) Shear force
b) Applied load
c) Internal reactions
d) All of the above
**Answer:** d) All of the above
54. The factor of safety is defined as:
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a) The ratio of ultimate strength to working stress
b) The ratio of working stress to ultimate strength
c) The ratio of load to allowable load
d) The ratio of allowable load to actual load
**Answer:** a) The ratio of ultimate strength to working stress
55. The centroid of a composite section is calculated by:
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a) Finding the centroid of each individual section and summing their moments
b) Taking the average of the centroid positions of the sections
c) Adding the areas of the sections and dividing by the total area
d) Using the section modulus of each part
**Answer:** a) Finding the centroid of each individual section and summing their moments
56. In the context of trusses, a member that only carries axial forces is considered:
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a) A rigid member
b) A bending member
c) A flexible member
d) An ideal truss member
**Answer:** d) An ideal truss member
57. The principle of moments states that:
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a) The algebraic sum of moments about any point is zero for a body in equilibrium
b) The sum of forces in any direction is zero for a body in equilibrium
c) The moment of inertia is constant
d) The total moment is equal to the sum of individual moments
**Answer:** a) The algebraic sum of moments about any point is zero for a body in equilibrium
58. In a static fluid, the pressure at a point depends on:
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a) The depth of the point below the surface
b) The density of the fluid
c) The gravitational acceleration
d) All of the above
**Answer:** d) All of the above
59. The principle of superposition states that:
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a) The net response at a point is the sum of the responses due to each individual load
b) The total deformation is equal to the sum of deformations due to individual forces
c) The combined effect of forces is independent of their positions
d) The effect of a force on a body can be divided into components
**Answer:** a) The net response at a point is the sum of the responses due to each individual load
60. The concept of “shear center” refers to:
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a) The point where the resultant shear force acts
b) The point where the shear force is maximized
c) The point at which bending moments are zero
d) The point where loads are applied
**Answer:** a) The point where the resultant shear force acts
61. In a uniform beam subjected to a central point load, the maximum bending moment occurs:
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a) At the supports
b) At the midpoint of the beam
c) Near the point load
d) At a distance equal to one-fourth of the span
**Answer:** b) At the midpoint of the beam
62. The strain energy stored in a material under deformation is proportional to:
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a) The square of the stress
b) The stress
c) The strain
d) The square of the strain
**Answer:** d) The square of the strain
63. The Euler’s buckling load for a column depends on:
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a) The length of the column
b) The modulus of elasticity
c) The moment of inertia of the column cross-section
d) All of the above
**Answer:** d) All of the above
64. The work done by a conservative force is:
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a) Path-dependent
b) Zero in a closed path
c) Equal to the product of force and distance
d) Independent of the path taken
**Answer:** d) Independent of the path taken
65. The maximum shear force in a simply supported beam with a uniformly distributed load occurs:
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a) At the midpoint of the beam
b) At the supports
c) One-quarter of the span from the supports
d) One-third of the span from the supports
**Answer:** b) At the supports
66. The term “stress concentration” refers to:
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a) Uniform distribution of stress in a material
b) Localized increase in stress around discontinuities
c) Decrease in stress in the region of an internal flaw
d) Uniform increase in stress in a material
**Answer:** b) Localized increase in stress around discontinuities
67. The equilibrium of a rigid body is achieved when:
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a) The sum of all forces and moments acting on the body are zero
b) The sum of forces is zero, but moments can be non-zero
c) The body is subjected to no external forces
d) The body is free to rotate
**Answer:** a) The sum of all forces and moments acting on the body are zero
68. The torsion formula is used to calculate:
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a) Shear stress in a cylindrical shaft
b) Bending stress in a beam
c) Axial stress in a column
d) Pressure in a fluid
**Answer:** a) Shear stress in a cylindrical shaft
69. The moment of inertia of a circular section about its diameter is given by:
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a) \( \frac{\pi d^4}{64} \)
b) \( \frac{\pi d^4}{32} \)
c) \( \frac{\pi d^3}{64} \)
d) \( \frac{\pi d^3}{32} \)
**Answer:** b) \( \frac{\pi d^4}{32} \)
70. In a dynamic system, the natural frequency depends on:
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a) The mass of the system
b) The stiffness of the system
c) Both mass and stiffness
d) The damping of the system
**Answer:** c) Both mass and stiffness
71. The bending stress in a beam is directly proportional to:
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a) The moment of inertia
b) The applied moment
c) The length of the beam
d) The distance from the neutral axis
**Answer:** d) The distance from the neutral axis
72. The principle of virtual work is primarily used in:
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a) Structural analysis
b) Fluid mechanics
c) Thermodynamics
d) Electromagnetism
**Answer:** a) Structural analysis
73. The neutral axis in a beam is the axis:
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a) Where the bending stress is maximum
b) Where the shear stress is maximum
c) Where there is no stress during bending
d) Where the moment is zero
**Answer:** c) Where there is no stress during bending
74. In engineering mechanics, “statics” deals with:
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a) Bodies in motion
b) Bodies at rest or in equilibrium
c) Forces in dynamic systems
d) None of the above
**Answer:** b) Bodies at rest or in equilibrium
75. The shear modulus of a material is a measure of:
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a) Its ability to resist deformation under shear stress
b) Its ability to resist axial deformation
c) Its ability to conduct heat
d) Its ability to absorb energy
**Answer:** a) Its ability to resist deformation under shear stress
76. The term “elastic limit” refers to:
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a) The maximum stress a material can withstand without permanent deformation
b) The maximum strain a material can withstand without failure
c) The point where a material starts to yield
d) The point where a material fractures
**Answer:** a) The maximum stress a material can withstand without permanent deformation
77. In a truss structure, the members that are subject to only axial forces are called:
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a) Rigid members
b) Pin-jointed members
c) Rigid-jointed members
d) Flexural members
**Answer:** b) Pin-jointed members
78. The deflection of a beam under a uniformly distributed load is:
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a) Maximum at the supports
b) Maximum at the center
c) Uniform along the length
d) Zero at the center
**Answer:** b) Maximum at the center
79. The term “free body diagram” refers to:
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a) A diagram showing all forces and moments acting on a body
b) A diagram showing