1000+ Engineering Mechanics Multiple Choice Question Answer [Solved]

1. The angle which an inclined plane makes with the horizontal when a body placed on it is about to move down is known as angle of
A. Friction
B. Limiting friction
C. Repose
D. Kinematic friction
Answer : C

2. The velocity ratio of a differential pulley block with D and d as the diameters of larger and smaller pulley, is
A. D/(D - d)
B. D/(D + d)
C. 2D/(D - d)
D. 2D/(D + d)
Answer : C

3. 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
Answer : C

4. 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
Answer : B

5. The law of motion involved in the recoil of gun is
A. Newton's first law of motion
B. Newton's second law of motion
C. Newton's third law of motion
D. None of these
Answer : C

6. A lead ball with a certain velocity is made to strike a wall, it falls down, but rubber ball of same mass and with same velocity strikes the same wall, it rebounds. Select the correct reason from the following:
A. Both the balls undergo an equal change in momentum
B. The change in momentum suffered by rubber ball is more than the lead ball
C. The change in momentum suffered by rubber ball is less than the lead ball
D. None of the above
Answer : B

7. The unit of work or energy in S.I. units is
A. Newton
B. Pascal
C. Watt
D. Joule
Answer : D

8. The velocity ratio of a first system of pulleys with 4 pulleys is
A. 4
B. 8
C. 16
D. 20
Answer : C

9. The C.G. of a solid hemisphere lies on the central radius 3r
A. At distance from the plane base 3r
B. At distance from the plane base 3r
C. At distance from the plane base 3r
D. At distance from the plane base
Answer : D

10. In a screw jack, the effort required to lift the load is given by (where W = Load lifted, ? = Helix angle, and ? = Angle of friction.)
A. P = W tan (? - ?)
B. P = W tan (? + ?)
C. P = W tan (? - ?)
D. P = W cos (? + ?)
Answer : B

11. A force while acting on a body may
A. Change its motion
B. Balance the forces, already acting on it
C. Give rise to the internal stresses in it
D. All of these
Answer : D

12. If a body is acted upon by a number of coplanar non-concurrent forces, it may
A. Rotate about itself without moving
B. Move in any one direction rotating about itself
C. Be completely at rest
D. All of these
Answer : D

13. The C.G. of a plane lamina will not be at its geometrical centre in the case of a
A. Right angled triangle
B. Equilateral triangle
C. Square
D. Circle
Answer : A

14. According to parallel axis theorem, the moment of inertia of a section about an axis parallel to the axis through centre of gravity (i.e. I_P) is given by(where, A = Area of the section, I_G = Moment of inertia of the section about an axis passing through its C.G., and h = Distance between C.G. and the parallel axis.)
A. I_P = I_G + Ah²
B. I_P = I_G - Ah²
C. I_P = I_G / Ah²
D. I_P = Ah² / I_G
Answer : A

15. The acceleration of a body sliding down an inclined surface is
A. g sin?
B. g cos?
C. g tan?
D. None of these
Answer : A

16. The law of the machine is (where P = Effort applied to lift the load, m = A constant which is equal to the slope of the line, W = Load lifted, and C = Another constant which represents the machine friction.)
A. P = mW - C
B. P = m/W + C
C. P = mW + C
D. P = C - mW
Answer : C

17. Which of the following is not the unit of energy?
A. kg m
B. kcal
C. Watt
D. Watt hours
Answer : C

18. A spherical body is symmetrical about its perpendicular axis. According to Routh's rule, the moment of inertia of a body about an axis passing through its centre of gravity is (where, M = Mass of the body, and S = Sum of the squares of the two semi-axes.)
A. MS/3
B. MS/4
C. MS/5
D. None of these
Answer : C

19. The force required to move the body up the plane will be minimum if it makes an angle with the inclined plane __________ the angle of friction.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : A

20. A trolley wire weighs 1.2 kg per meter length. The ends of the wire are attached to two poles 20 meters apart. If the horizontal tension is 1500 kg find the dip in the middle of the span
A. 2.5 cm
B. 3.0 cm
C. 4.0 cm
D. 5.0 cm
Answer : C

21. The moment of a force
A. Is the turning effect produced by a force, on the body, on which it acts
B. Is equal to the product of force acting on the body and the perpendicular distance of a point and the line of action of the force
C. Is equal to twice the area of the triangle, whose base is the line representing the force and whose vertex is the point, about which the moment is taken
D. All of the above
Answer : D

22. The linear velocity of a body rotating at ? rad/s along a circular path of radius r is given by
A. ?/r
B. ?.r
C. ?²/r
D. ?².r
Answer : B

23. When a person, on a bicycle, drives round a curve, he has to lean __________ to maintain equilibrium.
A. Inward
B. Outward
C. Towards front
D. Towards back
Answer : A

24. In actual 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
D. Mechanical advantage is unity
Answer : C

25. The bellow figure shows the two equal forces at right angles acting at a point. The value of force R acting along their bisector and in opposite direction is
A. P/2
B. 2P
C. ?2 × P
D. P/?2
Answer : C

26. If the resultant of two equal forces has the same magnitude as either of the forces, then the angle between the two forces is
A. 30°
B. 60°
C. 90°
D. 120°
Answer : D

27. A body of weight W is required to move up on rough inclined plane whose angle of inclination with the horizontal is ?. The effort applied parallel to the plane is given by (where ? = tan? = Coefficient of friction between the plane and the body.)
A. P = W tan?
B. P = W tan (? + ?)
C. P = W (sin? + ?cos?)
D. P = W (cos? + ?sin?)
Answer : C

28. The centre of gravity a T-section 100 mm × 150 mm × 50 mm from its bottom is
A. 50 mm
B. 75 mm
C. 87.5 mm
D. 125 mm
Answer : C

29. The C.G. of a right circular solid cone of height h lies at the following distance from the base
A. h/2
B. J/3
C. h/6
D. h/4
Answer : D

30. Which of the following statement is correct?
A. The algebraic sum of the forces, constituting the couple is zero
B. The algebraic sum of the forces, constituting the couple, about any point is the same
C. A couple cannot be balanced by a single force but can be balanced only by a couple of opposite sense
D. All of the above
Answer : D

31. In the shown figure, the tension (T) in the string will be
A. m?. m?. g/(m? + m?)
B. 2m?. m?. g/(m? + m?)
C. (m? + m?)/ m?. m?. g
D. (m? + m?)/2m?. m?. g
Answer : B

32. A smooth cylinder lying on its convex surface remains in __________ equilibrium.
A. Stable
B. Unstable
C. Neutral
D. None of these
Answer : B

33. One watt is equal to
A. 0.1 joule/s
B. 1 joule/s
C. 10 joules/s
D. 100 joules/s
Answer : B

34. 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
Answer : D

35. Static friction is always __________ dynamic friction.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : C

36. When the lift is moving upwards with some acceleration, the pressure exerted by a man is __________ to its acceleration.
A. Directly proportional
B. Inversely proportional
C. Cube root
D. None of these
Answer : A

37. 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
Answer : B

38. Effect of a force on a body depends upon
A. Magnitude
B. Direction
C. Position or line of action
D. All of the above
Answer : D

39. If tension in the cable supporting a lift moving downwards is half the tension when it is moving upwards, the acceleration of the lift is
A. g/2
B. g/3
C. g/4
D. None of these
Answer : D

40. In ideal machines, mechanical advantage is __________ velocity ratio.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : A

41. In order to determine the effects of a force, acting on a body, we must know
A. Magnitude of the force
B. Line of action of the force
C. Nature of the force i.e. whether the force is push or pull
D. All of the above
Answer : D

43. Two forces are acting at an angle of 120°. The bigger force is 40 N and the resultant is perpendicular to the smaller one. The smaller force is
A. 20 N
B. 40 N
C. 120 N
D. None of these
Answer : A

44. A redundant frame is also called __________ frame.
A. Perfect
B. Imperfect
C. Deficient
D. None of these
Answer : B

45. The rate of change of displacement of a body is called
A. Velocity
B. Acceleration
C. Momentum
D. None of these
Answer : A

46. The total energy possessed by a system of moving bodies
A. Is constant at every instant
B. Varies from point to point
C. Is maximum in the start and minimum at the end
D. Is minimum in the start and maximum at the end
Answer : A

47. A framed structure is perfect if it contains members equal to
A. 2n³
B. 2n
C. n²
D. 3n² Where n = number of joints in a frame
Answer : A

48. The three forces of 100 N, 200 N and 300 N have their lines of action parallel to each other but act in the opposite directions. These forces are known as
A. Coplanar concurrent forces
B. Coplanar non-concurrent forces
C. Like parallel forces
D. Unlike parallel forces
Answer : D

49. In a screw jack, the effort required to lower the load is __________ the effort required to raise the same load.
A. Less than
B. Equal to
C. More than
D. None of these
Answer : A

50. According to the law of moments, if a number of coplanar forces acting on a particle are in equilibrium, then
A. Their algebraic sum is zero
B. Their lines of action are at equal distances
C. The algebraic sum of their moments about any point in their plane is zero
D. The algebraic sum of their moments about any point is equal to the moment of their resultant force about the same point.
Answer : C