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IIFT - Engineering Mechanics 1000+ MCQ [Solved] PDF Download

Thursday 9th of March 2023

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Downlaod Engineering Mechanics MCQ PDF
1. 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
2. The point, through which the whole weight of the body acts, irrespective of its position, is known as
A. Moment of inertia
B. Centre of gravity
C. Centre of percussion
D. Centre of mass
Answer : B
3. 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
4. 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
5. The ideal angle of banking provided on the curves on roads depends upon
A. Weight of the vehicle
B. (Velocity)2 of the vehicle
C. Nature of the road surface
D. Coefficient of friction between the road and vehicle contact point
Answer : B
6. The friction experienced by a body, when in motion, is known as
A. Rolling friction
B. Dynamic friction
C. Limiting friction
D. Static friction
Answer : B
7. 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
8. 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
9. A force is completely defined when we specify
A. Magnitude
B. Direction
C. Point of application
D. All of the above
Answer : D
10. The moment of inertia of a square of side a about its diagonal is
A. a2/8
B. a3/12
C. a4/12
D. a4/16
Answer : C
11. 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
12. 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
13. 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
14. Forces are called concurrent when their lines of action meet in
A. One point
B. Two points
C. Plane
D. Perpendicular planes
Answer : A
15. Non-coplanar non-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. Do not meet at one point but their lines of action lie on the same plane
D. None of the above
Answer : B
16. 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
17. The moment of the force P about O as shown in the below figure is
A. P × OA
B. P × OB
C. P × OC
D. P × AC
Answer : C
18. Work done is said to be zero, when
A. Some force acts on a body, but displacement is zero
B. No force acts on a body but some displacement takes place
C. Either (A) or (B)
D. None of the above
Answer : C
19. The unit of energy in S.I. units is
A. Dyne
B. Watt
C. kg-m
D. Joule
Answer : D
20. 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
21. 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
22. 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
23. Centre of gravity of a thin hollow cone lies on the axis at a height of
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 : B
24. The force, by which the body is attracted, towards the centre of the earth, is called
A. Impulsive force
B. Mass
C. Weight
D. Momentum
Answer : C
25. 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
26. 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
27. 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
28. Which of the following statement is correct?
A. The algebraic sum of the forces, constituting the couple is zero
B. The algebraic sum of the forces, constituting the couple, about any point is the same
C. A couple cannot be balanced by a single force but can be balanced only by a couple of opposite sense
D. All of the above
Answer : D
29. 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
30. In order to completely specify angular displacement by a vector, it must fix
A. Direction of the axis of rotation
B. Magnitude of angular displacement
C. Sense of angular displacement
D. All of these
Answer : D
31. A body moves, from rest with a constant acceleration of 5 m per sec. The distance covered in 5 sec is most nearly
A. 38 m
B. 62.5 m
C. 96 m
D. 124 m
Answer : B
32. 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
33. 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
34. If the gravitational acceleration at any place is doubled, then the weight of a body will be
A. g/2
B. g
C. ?2.g
D. 2g
Answer : D
35. The moment of inertia of a square of side (a) about an axis through its centre of gravity is
A. a4/4
B. a4/8
C. a4/12
D. a4/36
Answer : C
36. In the shown figure, if the angle of inclination of the plane is increased, then acceleration of the system will
A. Increase
B. Decrease
C. Remain the same
D. None of these
Answer : B
37. The periodic time (T) is given by (where, ? = Angular velocity of particle in rad/s.)
A. ?/2?
B. 2?/?
C. 2? × ?
D. ?/?
Answer : B
38. Moment of inertia of a hollow circular section, as shown in the below figure about an axis perpendicular to the section, is __________ than that about X-X axis.
A. Two times
B. Same
C. Half
D. None of these
Answer : A
39. The rate of doing work is known as
A. Potential energy
B. Kinetic energy
C. Power
D. None of these
Answer : C
40. The time of fligt 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
41. The maximum mechanical advantage of a lifting machine is
A. 1 + m
B. 1 - m
C. 1 / m
D. m
Answer : C
42. 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
43. 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
44. 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
45. The rate of change of displacement of a body is called
A. Velocity
B. Acceleration
C. Momentum
D. None of these
Answer : A
46. The resultant of two forces P and Q acting at an angle ? is
A. ?(P² + Q² + 2PQ sin?)
B. ?(P² + Q² + 2PQ cos?)
C. ?(P² + Q² - 2PQ cos?)
D. ?(P² + Q² - 2PQ tan?)
Answer : B
47. 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. IP) is given by(where, A = Area of the section, IG = 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. IP = IG + Ah2
B. IP = IG - Ah2
C. IP = IG / Ah2
D. IP = Ah2 / IG
Answer : A
48. The unit of force in S.I. units is
A. kilogram
B. Newton
C. Watt
D. Dyne
Answer : B
49. 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
50. The coefficient of restitution for inelastic bodies is
A. Zero
B. One
C. Between zero and one
D. More than one
Answer : A
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