Engineering Mechanics

71. The forces, which meet at one point, but their lines of action do not lie in a plane, are called

1. coplanar non-concurrent forces
2. non-coplanar concurrent forces
3. non-coplanar non-concurrent forces
4. intersecting forces
5. none of the above.

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72. The M.I. of hollow circular section about a central axis perpendicular to section as compared to its M.I. about horizontal axis is

1. same
2. double
3. half
4. four times
5. one fourth.

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73. The magnitude of two forces, which when acting at right angle produce resultant force of VlOkg and when acting at 60° produce resultant of Vl3 kg. These forces are

1. 2 and V6
2. 3 and 1 kg
3. V5andV5
4. 2 and 5
5. none of the above.

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74. The necessary condition for forces to be in equilibrium is that these should be

1. coplanar
2. meet at one point ;
3. both (a) and (b) above
4. all be equal
5. something else.

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75. The possible loading in various members of framed structures are

1. compression or tension
2. buckling or shear
3. shear or tension
4. all of the above
5. bending.

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76. The product of either force of couple with the arm of the couple is called

1. resultant couple
2. moment of the forces
3. resulting couple
4. moment of the couple
5. none of the above.

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77. The ratio of limiting friction and normal reaction is known as

1. coefficient of friction
2. angle of friction
3. angle of repose
4. sliding friction
5. friction resistance.

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78. The resolved part of the resultant of two forces inclined at an angle 9 in a given direction is equal to

1. the algebraic sum of the resolved parts of the forces in the given direction
2. the sum of the resolved parts of the forces in the given direction
3. the difference of the forces multiplied by the cosine of 9
4. the sum of the forces multiplied by the sine of 9
5. the sum of the forces multiplied by the tangent of 9.

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79. 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

1. 20 kg, - ve sense
2. 20 kg, + ve sense
3. 10 kg, + ve sense
4. 10 kg, - ve sense
5. 45 kg, + ve sense.

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80. The unit of force in S.I. units is

1. kilogram
2. newton
3. watt
4. dyne
5. joule.

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