1000+ Engineering Mechanics Multiple Choice Question Answer [Solved]

1. 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

2. 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

3. Concurrent forces are those forces whose lines of action
A. Lie on the same line
B. Meet at one point
C. Meet on the same plane
D. None of these
Answer : B

4. 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

5. 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

6. 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

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

8. 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

9. 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

10. The centre of percussion of a solid cylinder of radius r resting on a horizontal plane will be
A. r/2
B. 2r/3
C. r/A
D. 3r/2
Answer : D

11. The moment of inertia of a solid cone of mass m and base radius r about its vertical axis is
A. 3mr²/5
B. 3mr²/10
C. 2mr²/5
D. 4mr²/5
Answer : B

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

13. 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

14. 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

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

16. 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

17. The overturning of a vehicle on a level circular path can be avoided if the velocity of vehicle is __________ ?(gra/h)
A. Less than
B. Greater than
C. Equal to
D. None of these
Answer : A

18. 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

19. 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

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

21. 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 machne
C. Mechanical advantage to the velocity ratio
D. All of the above
Answer : D

22. 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

23. The process of finding out the resultant force is called __________ of forces.
A. Composition
B. Resolution
C. Decomposition
D. None of these
Answer : A

24. 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

25. In actual 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 : C

26. 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

27. The moment of inertia of a thin disc of mass m and radius r, about an axis through its centre of gravity and perpendicular to the plane of the disc is
A. mr²/2
B. mr²/4
C. mr²/6
D. mr²/8
Answer : A

28. A differential pulley block has larger and smaller diameters of 100 mm and 80 mm respectively. Its velocity ratio is
A. 5
B. 10
C. 20
D. 40
Answer : B

29. The moment of inertia of a sphere of mass m and radius r, about an axis tangential to it, is
A. 2mr²/3
B. 2mr²/5
C. 7mr²/3
D. 7mr²/5
Answer : D

30. 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

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

32. 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

33. Coplanar non-concurrent forces are those forces which __________ at one point, but their lines of action lie on the same plane.
A. Meet
B. Do not meet
C. Either A or B
D. None of these
Answer : B

34. 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

35. A framed structure is perfect, if the number of members are __________ (2j - 3), where j is the number of joints.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : A

36. 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

37. 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

38. If three forces acting in one plane upon a rigid body, keep it in equilibrium, then they must either
A. Meet in a point
B. Be all parallel
C. At least two of them must meet
D. All the above are correct
Answer : D

39. If tension in the cable supporting a lift moving downwards is half the tension when it is moving upwards, the acceleration of the lift is
A. g/2
B. g/3
C. g/4
D. None of these
Answer : D

40. 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

41. When trying to turn a key into a lock, following is applied
A. Coplanar force
B. Non-coplanar forces
C. Moment
D. Couple
Answer : D

43. 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

44. 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

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

46. 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

47. 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

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. The linear acceleration (a) of a body rotating along a circular path of radius (r) with an angular acceleration of ? rad/s2, is
A. a = ?/ r
B. a = ?.r
C. a = r / ?
D. None of these
Answer : B

50. A lead ball with a certain velocity is made to strike a wall, it falls down, but rubber ball of same mass and with same velocity strikes the same wall, it rebounds. Select the correct reason from the following:
A. Both the balls undergo an equal change in momentum
B. The change in momentum suffered by rubber ball is more than the lead ball
C. The change in momentum suffered by rubber ball is less than the lead ball
D. None of the above
Answer : B