SSC Stenographer - Engineering Mechanics 1000+ MCQ [Solved] PDF Download

1. The mechanical advantage of a lifting machine is the ratio of
A. Distance moved by effort to the distance moved by load
B. Load lifted to the effort applied
C. Output to the input
D. All of the above
Answer : B

2. A heavy string attached at two ends at same horizontal level and when central dip is very small approaches the following curve
A. Circular arc
B. Parabola
C. Hyperbola
D. Elliptical
Answer : B

3. Coplanar non-concurrent forces are those forces which __________ at one point, but their lines of action lie on the same plane.
A. Meet
B. Do not meet
C. Either A or B
D. None of these
Answer : B

4. A pair of smith's tongs is an example of the lever of
A. Zeroth order
B. First order
C. Second order
D. Third order
Answer : C

5. The unit of energy in S.I. units is
A. Dyne
B. Watt
C. kg-m
D. Joule
Answer : D

6. The motion of a particle round a fixed axis is
A. Translatory
B. Rotary
C. Circular
D. Translatory as well as rotary
Answer : C

7. 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

8. A framed structure is imperfect, if the numbers of members are __________ (2j - 3).
A. Equal to
B. Less than
C. Greater than
D. Either (B) or (C)
Answer : D

9. 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

10. The centre of gravity of an isosceles triangle with base (p) and sides (q) from its base is
A. [?(4p² - q²)]/6
B. (4p² - q²)/6
C. (p² - q²)/4
D. (p² + q²)/4
Answer : A

11. The force induced in the string AB due to the load W, as shown in the below figure is
A. W sin?
B. W cos?
C. W sec?
D. W cosec?
Answer : D

12. 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
Answer : D

13. Pick up the incorrect statement from the following:
A. The C.G. of a circle is at its centre
B. The C.G. of a triangle is at the intersection of its medians
C. The C.G. of a rectangle is at the intersection of its diagonals
D. The C.G. of a semicircle is at a distance of r/2 from the centre
Answer : D

14. Forces are called concurrent when their lines of action meet in
A. One point
B. Two points
C. Plane
D. Perpendicular planes
Answer : A

15. The power developed by a body acted upon by a torque T Newton metre (N - m) and revolving at ? radian/s is given by
A. T.? (in watts)
B. T.?/60 (in watts)
C. T.?/75 (in kilowatts)
D. T.?/4500 (in kilowatts)
Answer : A

16. The ratio of static friction to dynamic friction is always
A. Equal to one
B. Less than one
C. Greater than one
D. None of these
Answer : C

17. If the masses of both the bodies, as shown in the below figure, are doubled, then the acceleration in the string will be
A. Same
B. Half
C. Double
D. None of these
Answer : A

18. The total momentum of a system of masses (i. e. moving bodies) in any one direction remains constant, unless acted upon by an external force in that direction. This statement is called
A. Newton's first law of motion
B. Newton's second law of motion
C. Principle of conservation of energy
D. Principle of conservation of momentum
Answer : D

19. The centre of gravity of a right circular solid cone is at a distance of __________ from its base, measured along the vertical axis. (where h = Height of a right circular solid cone.)
A. h/2
B. h/3
C. h/4
D. h/6
Answer : C

20. 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

21. The moment of inertia of a solid sphere of mass m and raius r is
A. 2mr²/3
B. 2mr²/5
C. mr²
D. mr²/2
Answer : B

22. Coulomb friction is the friction between
A. Bodies having relative motion
B. Two dry surfaces
C. Two lubricated surfaces
D. Solids and liquids
Answer : A

23. A smooth cylinder lying on a __________ is in neutral equilibrium.
A. Curved surface
B. Convex surface
C. Horizontal surface
D. None of these
Answer : C

24. The centre 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
Answer : A

25. The impact between two lead spheres is approximately equal to an __________ impact.
A. Elastic
B. Inelastic
C. Solid
D. None of these
Answer : B

26. The unit of power in S.I. units is
A. Horsepower
B. Joule
C. Watt
D. kg-m
Answer : C

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

28. The moment of inertia of a thin rod of mass m and length l, about an axis through its centre of gravity and perpendicular to its length is
A. ml²/4
B. ml²/ 6
C. ml²/8
D. ml²/12
Answer : D

29. The rate of change of momentum is directly proportional to the impressed force, and takes place in the same direction in which the force acts. This statement is known as
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 : B

30. The term 'Centroid' is
A. The same as centre of gravity
B. The point of suspension
C. The point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis
D. None of the above
Answer : A

31. 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
Answer : C

32. 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
Answer : B

33. 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
Answer : D

34. A particle moves along a straight line such that distance (x) traversed in t seconds is given by x = t² (t - 4), the acceleration of the particle will be given by the equation
A. 6t² - 8t
B. 3t² + 2t
C. 6f - 8
D. 6f - 4
Answer : C

35. 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

36. The maximum acceleration of a particle moving with simple harmonic motion is
A. ?
B. ?r
C. ?²r
D. ?/r
Answer : C

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. 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

39. The friction experienced by a body, when at rest, is known as
A. Static friction
B. Dynamic friction
C. Limiting friction
D. Coefficient of friction
Answer : A

40. The maximum velocity of a particle moving with simple harmonic motion is
A. ?
B. ?r
C. ?²r
D. ?/r
Answer : B

41. When a body of mass m attains a velocity v from rest in time t, then the kinetic energy of translation is
A. mv²
B. mgv²
C. 0.5 mv²
D. 0.5 mgv²
Answer : C

42. Moment of inertia of a circular section about its diameter (d) is
A. ?d³/16
B. ?d³/32
C. ?d⁴/32
D. ?d⁴/64
Answer : D

43. 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

44. A number of forces acting at a point will be in equilibrium, if
A. All the forces are equally inclined
B. Sum of all the forces is zero
C. Sum of resolved parts in the vertical direction is zero (i.e. ?V = 0)
D. None of these
Answer : C

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

46. The forces which meet at one point, but their lines of action __________ on the same plane, are Known as non-coplanar concurrent forces.
A. Lie
B. Do not lie
C. Either A or B
D. None of these
Answer : B

47. When the spring of a watch is wound, it will possess
A. Strain energy
B. Kinetic energy
C. Heat energy
D. Electrical energy
Answer : A

48. The centre of gravity of a trapezium with parallel sides a and b lies at a distance of y from the base b, as shown in the below figure. The value of y is
A. h [(2a + b)/(a + b)]
B. (h/2) [(2a + b)/(a + b)]
C. (h/3) [(2a + b)/(a + b)]
D. (h/3) [(a + b)/(2a + b)]
Answer : C

49. A block of mass 20 kg lying on a rough horizontal plane is connected by a light string passing over a smooth pulley to another mass 5 kg, which can move freely in the Vertical direction, as shown in the below figure. The tension in the string will __________ with the increase in coefficient of friction.
A. Increase
B. Decrease
C. Not be effected
D. None of these
Answer : A

50. 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