1000+ Engineering Mechanics Multiple Choice Question Answer [Solved]

1. The maximum efficiency of a screw jack is
A. (1 - sin?)/(1 + sin?)
B. (1 + sin?)/(1 - sin?)
C. (1 - tan?)/(1 + tan?)
D. (1 + tan?)/(1 - tan?)
Answer : A

2. 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

3. 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

4. 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

5. Which of the following statement is correct in connection with projectiles?
A. A path, traced by a projectile in the space, is known as trajectory.
B. The velocity, with which a projectile is projected, is known as the velocity of projection.
C. The angle, with the horizontal, at which a projectile is projected, is known as angle of projection.
D. All of the above
Answer : D

6. Two balls of equal mass and of perfectly elastic material are lying on the floor. One of the balls with velocity v is made to strike the second ball. Both the balls after impact will move with a velocity
A. v
B. v/2
C. v/4
D. v/8
Answer : B

7. The periodic time (T) is given by (where, ? = Angular velocity of particle in rad/s.)
A. ?/2?
B. 2?/?
C. 2? × ?
D. ?/?
Answer : B

8. Varingon's theorem of moments states that if a number of coplanar forces acting on a particle are in equilibrium, then
A. Their algebraic sum is zero
B. Their lines of action are at equal distances
C. The algebraic sum of their moments about any point in their plane is zero
D. The algebraic sum of their moments about any point is equal to the moment of their resultant force about the same point.
Answer : D

9. According to parallel axis theorem, the moment of inertia of a section about an axis parallel to the axis through centre of gravity (i.e. I_P) is given by(where, A = Area of the section, I_G = Moment of inertia of the section about an axis passing through its C.G., and h = Distance between C.G. and the parallel axis.)
A. I_P = I_G + Ah²
B. I_P = I_G - Ah²
C. I_P = I_G / Ah²
D. I_P = Ah² / I_G
Answer : A

10. 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

11. The frequency of oscillation of a compound pendulum is (where kG = Radius of gyration about the centroidal axis, and h = Distance between the point of suspension and C.G. of the body.)
A. 2?. ?(gh/kG² + h²)
B. 2?. ?(kG² + h²/gh)
C. 1/2?. ?(gh/kG² + h²)
D. 1/2?. ?(kG² + h²/gh)
Answer : C

12. 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

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

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. 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

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

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

18. The forces, which meet at one point, but their lines of action do not lie in a plane, are called
A. Coplanar non-concurrent forces
B. Non-coplanar concurrent forces
C. Non-coplanar non-concurrent forces
D. Intersecting forces
Answer : B

19. 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 ero
C. Algebraic sum of moments of all the forces about any point should be zero
D. All of the above
Answer : D

20. A machine having an efficiency greater than 50%, is known as
A. Reversible machine
B. Non-reversible machine
C. Neither reversible nor non-reversible machine
D. Ideal machine
Answer : A

21. The bellow figure shows the three coplanar forces P, Q and R acting at a point O. If these forces are in equilibrium, then
A. P/sin ? = Q/sin ? = R/sin ?
B. P/sin ? = Q/sin ? = R/sin ?
C. P/sin ? = Q/sin ? = R/sin ?
D. P/sin ? = Q/sin ? = R/sin ?
Answer : B

22. 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

23. The centre of gravity of a uniform lamina lies at
A. The centre of heavy portion
B. The bottom surface
C. The midpoint of its axis
D. All of the above
Answer : C

24. The velocity of a body on reaching the ground from a height h, is
A. 2.?(gh)
B. ?(gh)
C. ?(2gh)
D. 2g.?h
Answer : C

25. 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

26. 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

27. 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

28. 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

29. The product of either force of couple with the arm of the couple is called
A. Resultant couple
B. Moment of the forces
C. Resulting couple
D. Moment of the couple
Answer : D

30. 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

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

32. 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

33. 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

34. The energy possessed by a body, for doing work by virtue of its position, is called
A. Potential energy
B. Kinetic energy
C. Electrical energy
D. Chemical energy
Answer : A

35. Which of the following is the locus of a point that moves in such a manner that its distance from a fixed point is equal to its distance from a fixed line multiplied by a constant greater than one
A. Ellipse
B. Hyperbola
C. Parabola
D. Circle
Answer : B

36. In the lever of third order, load W, effort P and fulcrum F are oriented as follows
A. W between P and F
B. F between W and P
C. P between W and F
D. W, P and F all on one side
Answer : A

37. Which is the correct statement about law of polygon of forces?
A. If any number of forces acting at a point can be represented by the sides of a polygon taken in order, then the forces are in equilibrium
B. If any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon, then the forces are in equilibrium
C. If a polygon representing forces acting at a point is closed then forces are in equilibrium
D. If any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon taken in order, then the forces are in equilibrium
Answer : D

38. 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 plne
D. Do not meet at one point, but their lines of action lie on the same plane
Answer : C

39. 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

40. Which of the following statement is correct?
A. The kinetic energy of a body during impact remains constant.
B. The kinetic energy of a body before impact is equal to the kinetic energy of a body after impact.
C. The kinetic energy of a body before impact is less than the kinetic energy of a body after impact.
D. The kinetic energy of a body before impact is more than the kinetic energy of a body after impact.
Answer : D

41. 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

42. 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

43. 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

44. 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

45. Kinetic friction is the
A. Tangent of 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 : D

46. If two bodies having masses m₁ and m₂ (m₁>m₂) have equal kinetic energies, the momentum of body having mass m₁ is _________ the momentum of body having mass m₂.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : C

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

48. 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

49. In ideal machines
A. Mechanical advantage is greater than velocity ratio
B. Mechanical advantage is equal to velocity ratio
C. Mechanical advantage is less than velocity ratio
D. Mechanical advantage is unity
Answer : B

50. The C.G. of a right circular solid cone of height h lies at the following distance from the base
A. h/2
B. J/3
C. h/6
D. h/4
Answer : D