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

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

2. Coplanar concurrent forces are those forces which
A. Meet at one point, but their lines of action do not lie on the same plane
B. Do not meet at one point and their lines of action do not lie on the same plane
C. Meet at one point and their lines of action also lie on the same plane
D. Do not meet at one point, but their lines of action lie on the same plane
Answer : C

3. The resultant of the two forces P and Q is R. If Q is doubled, the new resultant is perpendicular to P. Then
A. P = Q
B. Q = R
C. Q = 2R
D. None of these
Answer : B

4. The maximum mechanical advantage of a lifting machine is
A. 1 + m
B. 1 - m
C. 1 / m
D. m
Answer : C

5. 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

6. 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

7. When two elastic bodies collide with each other,
A. The two bodies will momentarily come to rest after collision
B. The two bodies tend to compress and deform at the surface of contact
C. The two bodies begin to regain their original shape
D. All of the above
Answer : D

8. 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

9. 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

10. If the number of pulleys in a system is equal to its velocity ratio, then it is a __________ system of pulleys
A. First
B. Second
C. Third
D. None of these
Answer : B

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

12. A force is completely defined when we specify
A. Magnitude
B. Direction
C. Point of application
D. All of the above
Answer : D

13. Dynamic friction as compared to static friction is
A. Same
B. More
C. Less
D. May be less of more depending on nature of surfaces and velocity
Answer : C

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

15. 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

16. 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

17. 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

18. The efficiency of a lifting machine is the ratio of
A. Output to the input
B. Work done by the machine to the work done on the machine
C. Mechanical advantage to the velocity ratio
D. All of the above
Answer : D

19. 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

20. 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

21. Which of the followin is a scalar quantity?
A. Force
B. Speed
C. Velocity
D. Acceleration
Answer : B

22. 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

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

24. The velocity of a particle moving with simple harmonic motion is __________ at the mean position.
A. Zero
B. Minimum
C. Maximum
D. None of these
Answer : C

25. Center of percussion is
A. The point of C.G.
B. The point of metacenter
C. The point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis
D. Point of suspension
Answer : C

26. If a given force (or a given system of forces) acting on a body __________ the position of the body, but keeps it in equilibrium, then its effect is to produce internal stress in the body.
A. Change
B. Does not change
C. Changes periodically
D. None of these
Answer : B

27. The minimum force required to slide a body of weight W on a rough horizontal plane is
A. W sin?
B. W cos?
C. W tan?
D. None of these
Answer : C

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

29. The angle of inclination of the plane at which the body begins to move down the plane, is called
A. Angle of friction
B. Angle of repose
C. Angle of projection
D. None of these
Answer : A

30. Which of the following are vector quantities?
A. Angular displacement
B. Angular velocity
C. Angular acceleration
D. All of these
Answer : D

31. Mass moment of inertia of a uniform thin rod of mass M and length (l) about its mid-point and perpendicular to its length is
A. (2/3) Ml²
B. (1/3) Ml²
C. (3/4) Ml²
D. (1/12) Ml²
Answer : D

32. 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

33. 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)]
Answer : B

34. A force acting on a body may
A. Change its motion
B. Balance the other forces acting on it
C. Retard its motion
D. All of the above
Answer : D

35. The centre of gravity of a quadrant of a circle lies along its central radius (r) at a distance of
A. 0.5r
B. 0.6 r
C. 0.7 r
D. 0.8 r
Answer : B

36. If a suspended body is struck at the centre of percussion, then the pressure on die axis passing through the point of suspension will be
A. Maximum
B. Minimum
C. Zero
D. Infinity
Answer : C

37. If n = number of members and y = number of joints, then for a perfect frame, n = ?
A. 1/2
B. 2/3
C. 3/2
D. 2/4
Answer : B

38. 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
Answer : C

39. 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

40. 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

41. The wheels of a moving car possess
A. Potential energy only
B. Kinetic energy of translation only
C. Kinetic energy of rotation only
D. Kinetic energy of translation and rotation both
Answer : D

42. 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

43. The motion of a wheel of a car is
A. Purely translation
B. Purely rotational
C. Combined translation and rotational
D. None of these
Answer : C

44. 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

45. 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

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

47. A body will begin to move down an inclined plane if the angle of inclination of the plane is _________ the angle of friction.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : C

48. One joule means that
A. Work is done by a force of 1 N when it displaces a body through 1 m
B. Work is done by a force of 1 kg when it displaces a body through 1 m
C. Work is done by a force of 1 dyne when it displaces a body through 1 cm
D. Work is done by a force of 1 g when it displaces a body through 1 cm
Answer : A

49. 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

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