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Top 50 MCQ Engineering Mechanics

Subject ⇒Engineering Mechanics

1. 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

Ans : b

2.. The time of flight of a projectile on downward inclined plane depends upon
A. Angle of projection
B. Angle of inclination of the plane
C. Both (A) and (B)
D. None of these
Ans : c
3. In a single threaded worm and worm wheel, the number of teeth on the worm is 50. The diameter of the effort wheel is 100 mm and that of load drum is 50 mm. The velocity ratio is

A. 50
B. 100
C. 200
D. 400
Ans : b

4. The potential energy of a vertically raised body is __________ the kinetic energy of a vertically falling body.

A. Equal to
B. Less than
C. Greater than
D. None of these
Ans : a
5. A block of mass m₁, placed on an inclined smooth plane is connected by a light string passing over a smooth pulley to mass m₂, which moves vertically downwards as shown in the below figure. The tension in the string is

A. m₁/m₂
B. m₁. g. sin α
C. m₁.m₂/m₁ + m₂
D. m₁. m₂.g (1 + sin α)/(m₁ + m₂)
Ans : d
6.For any system of coplanar forces, the condition of equilibrium is that the
A. Algebraic sum of the horizontal components of all the forces should be zero
B. Algebraic sum of the vertical components of all the forces should be zero
C. Algebraic sum of moments of all the forces about any point should be zero
D. All of the above
Ans : d
7. Which of the following is not the unit of energy?
A. kg m
B. kcal
C. Watt
D. Watt hours
Ans : c
8. Which one of the following statements is not correct?
A. The tangent of the angle of friction is equal to coefficient of friction
B. The angle of repose is equal to angle of friction
C. The tangent of the angle of repose is equal to coefficient of friction
D. The sine of the angle of repose is equal to coefficient to friction
Ans : d
9. Moment of inertia of a hollow circular section, as shown in the below figure about X-axis, is

A. π/16 (D² – d²)
B. π/16 (D³ – d³)
C. π/32 (D⁴ – d⁴)
D. π/64 (D⁴ – d⁴)
Ans : d
10. The forces, whose lines of action are parallel to each other and act in the same directions, are known as
A. Coplanar concurrent forces
B. Coplanar non-concurrent forces
C. Like parallel forces
D. Unlike parallel forces
Ans : c

11. The velocity ratio in case of an inclined plane inclined at angle ‘θ’ to the horizontal and weight being pulled up the inclined plane by vertical effort is

A. sinθ
B. cosθ
C. tanθ
D. cosecθ
Ans : a

12. A screw jack used for lifting the loads is
A. A reversible machine
B. A non-reversible machine
C. An ideal machine
D. None of these
Ans : b

13. The maximum velocity of a particle moving with simple harmonic motion is
A. ω
B. ωr
C. ω2r
D. ω/r
Ans : b
14. A particle inside a hollow sphere of radius r, having coefficient of friction µ can rest up to height of
A. r/2
B. r/A
C. r/3
D. 0.134 r
Ans : d
15. 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
Ans : c
16. The range of projectile on a downward inclined plane is ________ the range on upward inclined plane for the same velocity of projection and angle of projection.
A. Less than
B. More than
C. Equal to
D. None of These
Ans : b
17 If the gravitational acceleration at any place is doubled, then the weight of a body will be
A. g/2
B. g
C. √2.g
D. 2g
Ans : d
18 A machine having an efficiency less than 50%, is known as
A. Reversible machine
B. Non-reversible machine
C. Neither reversible nor non-reversible machine
D. Ideal machine
Ans : b
19. Which is the correct statement about law of polygon of 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
Ans : d
20. Which of the following is an equation of linear motion?(where, u and v = Initial and final velocity of the body, a = Acceleration of the body, and s = Displacement of the body in time t seconds.)
A. v = u + a.t
B. s = u.t + ½ a.t2
C. v2 = u2 + 2a.s
D. All of these
Ans :d
21. The moment of inertia of a thin disc of mass ‘m’ and radius ‘r’, about an axis through its center of gravity and perpendicular to the plane of the disc is
A. mr²/2
B. mr²/4
C. mr²/6
D. mr²/8
Ans : a
22. If three forces acting in different planes can be represented by a triangle, these will be in
A. Non-equilibrium
B. Partial equilibrium
C. Full equilibrium
D. Unpredictable
Ans : a
23. The velocity ratio of a differential wheel and axle with ‘D’ as the diameter of effort wheel and d1 and d2 as the diameters of larger and smaller axles respectively, is
A. D/(d₁ + d₂)
B. D/(d₁ – d₂)
C. 2D/(d₁ + d₂)
D. 2D/(d₁ – d₂)
Ans :d
24. A circular hole of 50 mm diameter is cut out from a circular disc of 100 mm diameter as shown in the below figure. The center of gravity of the section will lie

A. In the shaded area
B. In the hole
C. At ‘O’
D. None of these
Ans :a
25. A framed structure is perfect if it contains members equal to (Where, n = number of joints in a frame)
A. 2n³
B. 2n
C. n²
D. 3n²
Ans :a
26. The velocity ratio of a simple wheel and axle with D and d as the diameters of effort wheel and load axle, is
A. D + d
B. D – d
C. D × d
D. D / d
Ans :d
27. 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
Ans :c
28. The range of projectile on a downward inclined plane is ________ the range on upward inclined plane for the same velocity of projection and angle of projection.
A. Less than
B. More than
C. Equal to
D. None of These
Ans :b
29. The coefficient of restitution for inelastic bodies is
A. Zero
B. One
C. Between zero and one
D. More than one
Ans :a
30. A flywheel on a motor goes from rest to 1000 rpm in 6 sec. The number of revolutions made is nearly equal to
25
B. 50
C. 100
D. 250
Ans :b
31. Which of the following is a scalar quantity?
A. Force
B. Speed
C. Velocity
D. Acceleration
Ans :b
32. Which of the following is a vector quantity?
A. Energy
B. Mass
C. Momentum
D. Angle
Ans :c
33. Which of the following statement is correct?
A. The periodic time of a particle moving with simple harmonic motion is the time taken by a particle for one complete oscillation
B. The periodic time of a particle moving with simple harmonic motion is directly proportional to its angular velocity
C. The velocity of the particle moving with simple harmonic motion is zero at the mean position
D. The acceleration of the particle moving with simple harmonic motion is maximum at the mean position
Ans :a
34. Which of the following statement is correct?
A. The kinetic energy of a body during impact remains constant
B. The kinetic energy of a body before impact is equal to the kinetic energy of a body after impact
C. The kinetic energy of a body before impact is less than the kinetic energy of a body after impact
D. The kinetic energy of a body before impact is more than the kinetic energy of a body after impact
Ans :d
35. Moment of inertia of a circular section about an axis perpendicular to the section is
A. πd3/16
B. πd3/32
C. πd4/32
D. πd4/64
Ans :c
36. The energy possessed by a body, for doing work by virtue of its position, is called
A. Potential energy
B. Kinetic energy
C. Electrical energy
D. Chemical energy
Ans :a
37. The coefficient of friction depends upon
A. Nature of surfaces
B. Area of contact
C. Shape of the surfaces
D. All of the above
Ans :a
38. The resultant of two equal forces ‘P’ making an angle ‘θ’, is given by
A. 2P sinθ/2
B. 2P cosθ/2
C. 2P tanθ/2
D. 2P cotθ/2
Ans :b
39. A framed structure is perfect, if the number of members are __________ (2j – 3), where j is the number of joints.
A. Equal to
B. Less than
C. Greater than
D. None of these
Ans :a
40. If a number of forces are acting at a point, their resultant is given by
A. (∑V)2 + (∑H)2
B. √[(∑V)2 + (∑H)2]
C. (∑V)2 +(∑H)2 +2(∑V)(∑H)
D. √[(∑V)2 +(∑H)2 +2(∑V)(∑H)]
Ans :b
41. The linear acceleration (a) of a body rotating along a circular path of radius (r) with an angular acceleration of α rad/s2, is
A. a = α/ r
B. a = α.r
C. a = r / α
D. None of these
Ans :b
42. The slope on the road surface generally provided on the curves is known as
A. Angle of friction
B. Angle of repose
C. Angle of banking
D. None of these
Ans :c
43. Coulomb friction is the friction between
A. Bodies having relative motion
B. Two dry surfaces
C. Two lubricated surfaces
D. Solids and liquids
Ans :a
44. 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
Ans :c
45. Two coplanar couples having equal and opposite moments
A. Balance each other
B. Produce a couple and an unbalanced force
C. Are equivalent
D. Cannot balance each other
Ans :d
46. If a number of forces are acting at a point, their resultant will be inclined at an angle ‘θ’ with the horizontal, such that
A. tanθ = ΣH/ΣV
B. tanθ = ΣV/ΣH
C. tanθ = ΣV × ΣH
D. tanθ = √(ΣV + ΣH)
Ans :b
47. 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
Ans :d
48. When trying to turn a key into a lock, following is applied
A. Coplanar force
B. Non-coplanar forces
C. Moment
D. Couple
Ans :d
49. Joule is the unit of
A. Force
B. Work
C. Power
D. Velocity
Ans :b
50. In a screw jack, the effort required to lift the load is given by (where W = Load lifted, α = Helix angle, and φ = Angle of friction.)
A. P = W tan (α – φ)
B. P = W tan (α + φ)
C. P = W tan (φ – α)
D. P = W cos (α + φ)
Ans :b

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