1000+ Engineering Mechanics MCQ for RRB JE [Solved]

1. 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

2. 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

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

4. 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

5. A projectile is fired at an angle ? to the vertical. Its horizontal range will be maximum when ? is
A. 0°
B. 30°
C. 45°
D. 60°
Answer : C

6. If three forces acting in different planes can be represented by a triangle, these will be in
A. Non-equilibrium
B. Partial equilibrium
C. Full equilibrium
D. Unpredictable
Answer : A

7. The forces, which meet at one point and their lines of action also lie on the same plane, are known as
A. Coplanar concurrent forces
B. Coplanar non-concurrent forces
C. Non-coplanar concurrent forces
D. Non-coplanar non-concurrent forces
Answer : A

8. 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

9. The horizontal range of a projectile (R) is given by
A. R = u² cos2?/g
B. R = u² sin2?/g
C. R = u² cos?/g
D. R = u² sin?/g
Answer : B

10. Which of the following is not the unit of power?
A. kW (kilowatt)
B. hp (horse power)
C. kcal/sec
D. kcal/kg sec
Answer : D

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

12. The coefficient of restitution for inelastic bodies is
A. Zero
B. One
C. Between zero and one
D. More than one
Answer : A

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

14. 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

15. 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

16. 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

17. Mass moment of inertia of a thin rod about its one end is __________ the mass moment of inertia of the same rod about its midpoint
A. Same as
B. Twice
C. Thrice
D. Four times
Answer : D

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

19. Which of the following is not a scalar quantity?
A. Mass
B. Volume
C. Density
D. Acceleration
Answer : D

20. Lami's theorem states that
A. Three forces acting at a point will be in equilibrium
B. Three forces acting at a point can be represented by a triangle, each side being proportional to force
C. If three forces acting upon a particle are represented in magnitude and direction by the sides of a triangle, taken in order, they will be in equilibrium
D. If three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two
Answer : D

21. If the masses of both the bodies, as shown in the below figure, are reduced to 50 percent, then tension in the string will be
A. Same
B. Half
C. Double
D. None of these
Answer : B

22. 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

23. Coefficient 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 friction force acting when the body is just about to move
D. The friction force acting when the body is in motion
Answer : B

24. Tangent of angle of friction is equal to
A. Kinetic friction
B. Limiting friction
C. Angle of repose
D. Coefficient of friction
Answer : D

25. For any system of coplanar forces, the condition of equilibrium is that the
A. Algebraic sum of the horizontal components of all the forces should be zero
B. Algebraic sum of the vertical components of all the forces should be zero
C. Algebraic sum of moments of all the forces about any point should be zero
D. All of the above
Answer : D

26. 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

27. 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

28. The ratio of limiting friction and normal reaction is known as
A. Coefficient of friction
B. Angle of friction
C. Angle of repose
D. Sliding friction
Answer : A

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

30. 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

31. 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

32. Two coplanar couples having equal and opposite moments
A. Balance each other
B. Produce a couple and an unbalanced force
C. Are equivalent
D. Cannot balance each other
Answer : D

33. 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

34. 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

35. A circular hole of 50 mm diameter is cut out from a circular disc of 100 mm diameter as shown in the below figure. The centre of gravity of the section will lie
A. In the shaded area
B. In the hole
C. At O
D. None of these
Answer : A

36. 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

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

38. 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

39. 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

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

41. 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

42. In a framed structure, as shown in the below figure, the forces in the members AB and BC are respectively
A. ?3. W (tensile) and 2W (compressive)
B 2W (tensile) and ?3. W (compressive)
C. 2?3. W (tensile) and 2?3. W (compressive)
D. None of the above
Answer : A

43. 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

44. 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

45. When a body of mass moment of inertia I (about a given axis) is rotated about that axis with an angular velocity to, then the kinetic energy of rotation is
A. I?
B. I?²
C. 0.5 I?
D. 0.5 I?²
Answer : D

46. The maximum efficiency of a lifting machine is
A. 1/m
B. V.R./m
C. m/V.R.
D. 1/(m × V.R.)
Answer : D

47. 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

48. 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

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

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