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

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

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

3. The angle between two forces when the resultant is maximum and minimum respectively are:
A. 0° and 180°
B. 180° and 0°
C. 90° and 180°
D. 90° and 0°
Answer : A

4. The velocity ratio of a single purchase crab winch can be increased by
A. Increasing the length of the handle
B. Increasing the radius of the load drum
C. Increasing the number of teeth of the pinion
D. All of the above
Answer : A

5. 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

6. A flywheel on a motor goes from rest to 1000 rpm in 6 sec. The number of revolutions made is nearly equal to
A. 25
B. 50
C. 100
D. 250
Answer : B

7. A body moves, from rest with a constant acceleration of 5 m per sec. The distance covered in 5 sec is most nearly
A. 38 m
B. 62.5 m
C. 96 m
D. 124 m
Answer : B

8. 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
Answer : C

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

10. 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

11. Which of the following do not have identical dimensions?
A. Momentum and impulse
B. Torque and energy
C. Torque and work
D. Moment of a force and angular momentum.
Answer : D

12. According to Newton's first law of motion,
A. Everybody continues in its state of rest or of uniform motion, in a straight line, unless it is acted upon by some external force
B. 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
C. To every action, there is always an equal and opposite reaction
D. None of the above
Answer : A

13. 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 ?
C. m₁.m₂/m₁ + m₂
D. m₁. m₂.g (1 + sin ?)/(m₁ + m₂)
Answer : D

14. The moment of inertia of a solid cylinder of mass m, radius r and length l about the longitudinal axis or polar axis is
A. mr²/2
B. mr²/4
C. mr²/6
D. mr²/8
Answer : A

15. The unit of moment of inertia of an area is
A. kg-m²
B. kg-m-s²
C. kg/m²
D. m⁴
Answer : D

16. Moment of inertia of a hollow rectangular section as shown in the below figure about X-X axis, is
A. (BD³/12) - (bd³/12)
B. (DB³/12) - (db³/12)
C. (BD³/36) - (bd³/36)
D. (DB³/36) - (db³/36)
Answer : A

17. A ladder is resting on a smooth ground and leaning against a rough vertical wall. The force of friction will act
A. Towards the wall at its upper end
B. Away from the wall at its upper end
C. Downward at its upper end
D. Upward at its upper end
Answer : D

18. Centre 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
Answer : B

19. Efficiency of a screw jack is given by (where ? = Helix angle, and ? = Angle of friction.)
A. tan(? + ?)/tan?
B. tan?/tan (? + ?)
C. tan(? - ?)/tan?
D. None of these
Answer : B

20. The moment of inertia of a square of side (a) about an axis through its centre of gravity is
A. a⁴/4
B. a⁴/8
C. a⁴/12
D. a⁴/36
Answer : C

21. Which of the following is not a vector quantity?
A. Weight
B. Velocity
C. Acceleration
D. Force
Answer : A

22. The total motion possessed by a body, is called
A. Impulsive force
B. Mass
C. Weight
D. Momentum
Answer : D

23. The velocity ratio for the first system of pulleys is (where n is the number of pulleys.)
A. n
B. n²
C. 2n
D. 2n - 1
Answer : C

24. The friction experienced by a body, when in motion, is known as
A. Rolling friction
B. Dynamic friction
C. Limiting friction
D. Static friction
Answer : B

25. Two blocks A and B of masses 150 kg and 50 kg respectively are connected by means of a string as shown in the below figure. The tension in all the three strings __________ be same.
A. Will
B. Will not
C. Either A or B
D. None of these
Answer : A

26. Moment of inertia of a circular section about an axis perpendicular to the section is
A. ?d³/16
B. ?d³/32
C. ?d⁴/32
D. ?d⁴/64
Answer : C

27. Moment of inertia of a triangular section of base (b) and height (h) about an axis passing through its vertex and parallel to the base, is __________ than that passing through its C.G. and parallel to the base.
A. Nine times
B. Six times
C. Four times
D. Two times
Answer : A

28. The algebraic sum of moments of the forces forming couple about any point in their plane is
A. Equal to the moment of the couple
B. Constant
C. Both of above are correct
D. Both of above are wrong
Answer : A

29. 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

30. Joule is the unit of
A. Force
B. Work
C. Power
D. Velocity
Answer : B

31. The time of flight (t) of a projectile on an upward inclined plane is (where u = Velocity of projection, ? = Angle of projection, and ? = Inclination of the plane with the horizontal.)
A. t = g cos ?/2u sin (? - ?)
B. t = 2u sin (? - ?)/g cos ?
C. t = g cos ?/2u sin (? + ?)
D. t = 2u sin (? + ?)/g cos ?
Answer : B

32. Three forces acting on a rigid body are represented in magnitude, direction and line of action by the three sides of a triangle taken in order. The forces are equivalent to a couple whose moment is equal to
A. Area of the triangle
B. Twice the area of the triangle
C. Half the area of the triangle
D. None of these
Answer : B

33. The resultant of two equal forces P making an angle ?, is given by
A. 2P sin?/2
B. 2P cos?/2
C. 2P tan?/2
D. 2P cot?/2
Answer : B

34. 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

35. A semicircular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi circular disc and horizontal surface is ?. This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will
A. Remain horizontal
B. Slant up towards direction of pull
C. Slant down towards direction of pull
D. None of the above
Answer : C

36. A particle inside a hollow sphere of radius r, having coefficient of friction ? can rest up to height of
A. r/2
B. r/A
C. r/3
D. 0.134 r
Answer : D

37. 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

38. 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

39. The rate of doing work is known as
A. Potential energy
B. Kinetic energy
C. Power
D. None of these
Answer : C

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

41. In order to completely specify angular displacement by a vector, it must fix
A. Direction of the axis of rotation
B. Magnitude of angular displacement
C. Sense of angular displacement
D. All of these
Answer : D

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

44. The velocity of a particle (v) moving with simple harmonic motion, at any instant is given by (where r = Amplitude of motion, and y = Displacement of the particle from mean position.)
A. ?.?(y² - r²)
B. ?.?(r² - y²)
C. ?².?(y² - r²)
D. ?².?(r² - y²)
Answer : B

45. 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

46. The static friction
A. Bears a constant ratio to the normal reaction between the two surfaces
B. Is independent of the area of contact, between the two surfaces
C. Always acts in a direction, opposite to that in which the body tends to move
D. All of the above
Answer : D

47. During elastic impact, the relative velocity of the two bodies after impact is __________ the relative velocity of the two bodies before impact.
A. Equal to
B. Equal and opposite to
C. Less than
D. Greater than
Answer : B

48. The velocity ratio for the third system of pulleys is
A. n
B. n²
C. 2n
D. 2n - 1
Answer : D

49. The force, by which the body is attracted, towards the centre of the earth, is called
A. Impulsive force
B. Mass
C. Weight
D. Momentum
Answer : C

50. 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