RRB Group D - Engineering Mechanics 1000+ MCQ [Solved] PDF Download

1. The velocity ratio in case of an inclined plane inclined at angle ? to the horizontal and weight being pulled up the inclined plane by vertical effort is
A. sin?
B. cos?
C. tan?
D. cosec?
Answer : A

2. Centre of gravity of a solid cone lies on the axis at the height
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 : A

3. A heavy ladder resting on floor and against a vertical wall may not be in equilibrium, if
A. The floor is smooth, the wall is rough
B. The floor is rough, the wall is smooth
C. The floor and wall both are smooth surfaces
D. The floor and wall both are rough surfaces
Answer : C

4. 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

5. 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

6. The resultant of the following three couples 20 kg force, 0.5 m arm, +ve sense 30 kg force, 1 m arm, -ve sense 40 kg force, 0.25 m arm, +ve sense having arm of 0.5 m will be
A. 20 kg, -ve sense
B. 20 kg, + ve sense
C. 10 kg, + ve sense
D. 10 kg, -ve sense
Answer : A

7. A sample of metal weighs 219 gms in air, 180 gms in water, 120 gms in an unknown fluid. Then which is correct statement about density of metal
A. Density of metal can't be determined
B. Metal is twice as dense as water
C. Metal will float in water
D. Metal is twice as dense as unknown fluid
Answer : A

8. The amplitude is always __________ radius of the circle.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : A

9. The periodic time of one oscillation for a simple pendulum is (where l = Length of the pendulum.)
A. (1/2?). ?(l/g)
B. (1/2?). ?(g/l)
C. 2?. ?(l/g)
D. None of these
Answer : C

10. 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

11. 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

12. Moment of inertia is the
A. Second moment of force
B. Second moment of area
C. Second moment of mass
D. All of these
Answer : D

13. The length of a second's pendulum is
A. 94.9 cm
B. 99.4 cm
C. 100 cm
D. 101 cm
Answer : B

14. If u₁ and u₂ are the velocities of two moving bodies in the same direction before impact and v₁ and v₂ are their velocities after impact, then coefficient of restitution is given by
A. (v₁ - v₂)/(u₁ - u₂)
B. (v? - v?)/(u₁ - u₂)
C. (u₁ - u₂)/(v₁ - v₂)
D. (u? + u?)/(v? + v?)
Answer : B

15. Moment of inertia of a triangular section of base (b) and height (h) about an axis through its base, is
A. bh³/4
B. bh³/8
C. bh³/12
D. bh³/36
Answer : C

16. 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.
Answer : A

17. 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

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 range of a projectile is maximum, when the angle of projection is
A. 30°
B. 45°
C. 60°
D. 90°
Answer : B

20. 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

21. A single force and a couple acting in the same plane upon a rigid body
A. Balance each other
B. Cannot balance each other
C. Produce moment of a couple
D. Are equivalent
Answer : B

22. 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

23. The weight of a body is due to
A. Gravitational pull exerted by the earth
B. Forces experienced by body in atmosphere
C. Force of attraction experienced by particles
D. Gravitational force of attraction towards the centre of the earth
Answer : D

24. Moment of inertia of a hollow circular section, as shown in the below figure about X-axis, is
A. ?/16 (D² - d²)
B. ?/16 (D³ - d³)
C. ?/32 (D? - d?)
D. ?/64 (D? - d?)
Answer : D

25. 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
Answer : D

26. 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

27. 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

28. 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

29. The units of moment of inertia of an area are
A. kg-m²
B. m?
C. kg/m²
D. m³
Answer : B

30. The unit of force in S.I. system of units is
A. Dyne
B. Kilogram
C. Newton
D. Watt
Answer : C

31. A pendulum which executes one beat per second is known as
A. Simple pendulum
B. Compound pendulum
C. Torsional pendulum
D. Second's pendulum
Answer : D

32. Which of the following statement is incorrect?
A. A force acting in the opposite direction to the motion of the body is called force of friction
B. The ratio of the limiting friction to the normal reaction is called coefficient of friction
C. A machine whose efficiency is 100% is known as an ideal machine
D. The velocity ratio of a machine is the ratio of load lifted to the effort applied
Answer : D

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 body falls freely under gravity, then the gravitational acceleration is taken as
A. +8.9 m/s²
B. -8.9 m/s²
C. +9.8 m/s²
D. -9.8 m/s²
Answer : C

35. 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

36. 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

37. The units of moment of inertia of mass are
A. kg-m²
B. m²/kg.
C. kg/m²
D. kg/m
Answer : A

38. 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

39. Pick up wrong statement about friction force for dry surfaces. Friction force is
A. Proportional to normal load between the surfaces
B. Dependent on the materials of contact surface
C. Proportional to velocity of sliding
D. Independent of the area of contact surfaces
Answer : C

40. 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
Answer : B

41. The periodic time of a particle with simple harmnic motion is __________ proportional to the angular velocity.
A. Directly
B. Inversely
C. Square root
D. None of these
Answer : B

42. Angle of friction is the
A. Angle between normal reaction and the resultant of normal reaction and the limiting friction
B. Ratio of limiting friction and normal reaction
C. The ratio of minimum friction force to the friction force acting when the body is just about to move
D. The ratio of minimum friction force to friction force acting when the body is in motion
Answer : A

43. 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

44. On a ladder resting on smooth ground and leaning against vertical wall, the force of friction will be
A. Towards the wall at its upper end
B. Away from the wall at its upper end
C. Upwards at its upper end
D. Downwards at its upper end
Answer : C

45. 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

46. The forces which do not meet at one point and their lines of action do not lie on the same plane are known as
A. Coplanar concurrent forces
B. Coplanar non-concurrent forces
C. Non-coplanar concurrent forces
D. None of these
Answer : D

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 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
Answer : C

49. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as
A. Static friction
B. Dynamic friction
C. Limiting friction
D. Coefficient of friction
Answer : C

50. The principle of transmissibility of forces states that, when a force acts upon a body, its effect is
A. Same at every point on its line of action
B. Different at different points on its line of action
C. Minimum, if it acts at the centre of gravity of the body
D. Maximum, if it acts at the centre of gravity of the body
Answer : C