### Tribology (MCQ : MODULE - 2)

Question 1: Which one of the following statements is NOT true about friction?

 A. Friction is tangential resistance to motion. B. Friction is dependent upon the surface of the content. C. Friction is greater on rough surface. D. Friction does not decrease with lubrication.

(A)
(B)
(C)
(D)

Question 2: Coefficient of friction is independent of

 A. Temperature. B. Surface Roughness. C. Hardness. D. Surface area of contact.

(A)
(B)
(C)
(D)

Question 3: Phenomenon of stick-slip occurs because of

 A. Large difference between static and kinetic coefficients of friction. B. Additional force requirement to move the object. C. Increase in hardness of surfaces. D. Lubrication is applied on the surfaces.

(A)
(B)
(C)
(D)

Question 4: Adhesion component of dry friction is negligible at interface of

 A. High temperature surfaces. B. Lubricated tribo pair. C. Rough surfaces. D. Extra smooth surfaces.

(A)
(B)
(C)
(D)

Question 5: Cold weld between two surfaces happens because of

 A. Excessive lubrication. B. Adhesion between two surfaces. C. Relatively high surface roughness. D. Low temp on area of contact.

(A)
(B)
(C)
(D)

Question 6: As per the ploughing theory of friction, which of the following statements is not true?

 A. Slope of asperities govern the friction force. B. Sharp asperities causes more friction compared to round or spherical asperities. C. Asperities on one surface interact with the asperities or valleys on the other surface. D. An asperity of softer surface causes ploughing on the harder surface.

(A)
(B)
(C)
(D)

Question 7: The formation of junction growth can be reduced by

 A. Lubrication of the surfaces. B. Increasing the surface finish of the rubbing surfaces. C. Annealing the surfaces. D. All of above.

(A)
(B)
(C)
(D)

Question 8: Deformation of asperities causes

 A. Increase in friction. B. Decrease in friction. C. Can increase or decrease friction. D. No effect.

(A)
(B)
(C)
(D)

Question 9: Ploughing effect causes

 A. Piercing and penetration of the soft surface by the asperities of the hard surface. B. Increasing in friction. C. Both (a) & (b). D. None of these.

(A)
(B)
(C)
(D)

Question 10: Coefficient of friction due to rolling is generally

 A. Greater than coefficient of sliding friction. B. Lesser than coefficient of sliding friction. C. Equal to sliding friction. D. May be greater or smaller compared to sliding friction.

(A)
(B)
(C)
(D)

Question 11: Which of the following are the major contributors to rolling friction?

 A. Micro-slip effect within the contact area. B. Elastic hysteresis of the contacting materials. C. Plastic deformation of the materials& adhesion effects in the contact. D. All of the above.

(A)
(B)
(C)
(D)

Question 12: Which one of the following is truefor ball bearings?

I. Sliding occurs between cage and balls.

II. Lubricants such as grease are used to reduce friction within ball bearing.

III. Cages are meant to bear the load.

 A. Both (I) and (II). B. Both (I) and (III). C. Both (II) and (III). D. All three (I), (II) and (III).

(A)
(B)
(C)
(D)

Question 13: If an automobile tire is not filled up to the optimum pressure level it means:

 A. There would be less hysteresis loss. B. Rolling friction would be lower. C. More steering controllability. D. None of these.

(A)
(B)
(C)
(D)

Question 14: To avoid the phenomenon of stick slip due to friction instability which of the following is the right approach?

 A. Increase the operation speed. B. Decrease the operation speed. C. Operation speed does not have any effect on the stick slip process. D. Increase the difference between static and kinetic coefficient of friction.

(A)
(B)
(C)
(D)

Question 15: In a mechanical system, negative damping due to friction instability causes

 A. Increase in vibration amplitude over a period of time. B. Decrease in vibration amplitude over a period of time. C. Amplitude remains unchanged with time. D. None of these.

(A)
(B)
(C)
(D)

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