# Machine Design Questions and Answers – Hydrodynamics Step Bearing

This set of Machine Design Multiple Choice Questions & Answers (MCQs) focuses on “Hydrodynamics Bearings”.

1. The bearing characteristic number shown in the graph is directly proportional to the unit bearing pressure.

a) True
b) False

Explanation: BCN=µN/P.

2. In the graph shown below, which regions points the partial metal to metal contact.

a) BC
b) CD
c) Both BC and CD
d) Can’t be determined

Explanation: BC is the condition of thin film and hence surfaces are not completely separated.

3. Hydrodynamic lubrication takes place in which region?

a) BC
b) CD
c) Both BC and CD
d) None of the mentioned

Explanation: In CD thick film of lubrication has developed.

4. Coefficient of friction is minimum at

a) It is same at each point
b) B
c) C
d) D

Explanation: It is minimum at the transition zone.

5. Bearing modulus is the bearing characteristic number at

a) B
b) C
c) D
d) None of the listed

Explanation: BCN modulus is the the BCN number corresponding to the minimum coefficient of friction.
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6. If viscosity of the lubricant is very low than BCN will lie in the region.

a) BC
b) Point C
c) CD
d) Can’t be determined

Explanation: Due to low viscosity, lubricant will not separate the two surfaces resulting in partial contact.

7. The fundamental equation for viscous flow is given by ∆pbhᵌ/6µl where symbols have their usual meanings.
a) 6 is to be replaced by 3
b) 6 is to be replaced by 12
c) 6 is to be replaced by 9
d) 6 is to be replaced by 15

Explanation: It is givenby ∆pbhᵌ/12µl.

8. A single transverse weld is preferred over double transverse fillet weld.
a) True
b) False

Explanation: A single transverse weld is not preferred because the edge of the plate which is not welded can warp out of shape.

9. Transverse fillet weld can be designed using the same equations as of parallel fillet weld.
a) True
b) False

Explanation: Vice versa is true as strength of transverse fillet weld is greater than that of parallel fillet weld.

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