Strength of Materials MCQs

52. Which is the correct statement about law of polygon of forces ?

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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
✅ The correct answer is option D.

53. Which one of the following statements is not correct_________________?

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A. the tangent of the angle of friction is equal to coefficient of friction
B. the angle of repose is equal to angle of friction
C. the tangent of the angle of repose is equal to coefficient of friction
D. the sine of the angle of repose is equal to coefficient to friction
✅ The correct answer is option D.

54. Pick up wrong statement about friction force for dry surfaces. Friction force is________________?

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A. proportional to normal load between the surfaces
B. dependent on the materials of contact surface
C. proportional to velocity of sliding
D. independent of the area of contact surfaces
✅ The correct answer is option C.

58. According to principle of transmissibility of forces, the effect of a force upon a body is_______________?

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A. maximum when it acts at the center of gravity of a body
B. different at different points in its line of action
C. the same at every point in its line of action
D. minimum when it acts at the C.G. of the body
✅ The correct answer is option C.

59. Kinetic friction is the________________?

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A. tangent of angle between normal reac-tion and the resultant of normal reac-tion 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
✅ The correct answer is option D.