### Tribology (MCQ : MODULE - 5)

Question 1: The lowest friction producing fluid film mechanism is

 A. Elasto-hydrodynamic lubrication. B. Hydrodynamic lubrication. C. Mixed lubrication. D. Boundary lubrication.

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

Question 2: Which one of following does not belong to equations required to estimate fluid film pressure?

 A. Reynoldsĺs equation. B. Bernoulli equation. C. Continuity equation. D. Navier Stokes equation.

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

Question 3: Petroffĺs equation is used for

 A. Rough estimation of friction loss in sliding bearing. B. Change in viscosity wrt to temperature. C. Change in density wrt to temperature. D. Both (a) & (b).

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

Question 4: Which one of the following expressions represents the pressure term in Reynoldsĺs Equation for incompressible lubricants?

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

Question 5: Which equation is used to model the pressure distribution in elastohydrodynamic lubrication between spherical contacts?

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

Question 6: Which of the following equation is used to model the pressure distribution in elastohydrodynamic lubrication between cylindrical contacts?

A. B. C. D. None of these

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

Question 7: The total applied load between spherical contacts in elastohydrodynamic lubrication can be calculated using the equation :

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

Question 8: The total applied load between cylindrical contacts in elastohydrodynamic lubrication can be calculated using the equation :

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

Question 9: To calculate the total applied load between spherical and cylindrical contacts in elastohydrodynamic lubrication, the elastic deformation as suggested by Timoshenko & Goodiercan be calculated using the equation :

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

Question 10: Load capacity of cylindrical contact compared to spherical contact is :

 A. Higher. B. Smaller. C. Similar. D. Cannot be compared without specifying dimensions.

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

Question 11: Due to elastic deformation along the contact patch in elastohydrodynamic lubrication, the maximum value of the pressure :

 A. Increases. B. Decreases. C. Remains same. D. Cannot be said.

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

Question 12: Thermohydrodynamic lubrication is referred as :

 A. Hydrodynamic lubrication with allowance for viscous heating. B. Lubrication mechanism which does not allow viscous heating. C. Hydrodynamic lubrication in which heating of the lubricant cannot occur. D. None of these.

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

Question 13: In journal bearing, friction loss can be represented as :

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

Question 14: Which among the following represent the value of Φ for Newtonian fluid in the energyequation?

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

Question 15: For practical purposes the friction force in hydrodynamic lubrication is represented as :

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

Question 16: Which of the fluid film lubrication mechanism is suitable for very high loads moving at low speeds like large telescopes, radar tracking units, machine tools and gyroscopes?

 A. Hydrodynamic lubrication. B. Hydrostatic lubrication. C. Squeeze film lubrication. D. Aerostatic lubrication.

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

Question 17: In hydrodynamic lubrication minimum film thickness (hmin), a critical design criterion, is a function of :

 A. Relative velocity (U). B. Applied load (W). C. Viscosity. D. All of above.

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

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