Fluid Mechanics Questions and Answers – Power Absorbed in Viscous Flow

This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Power Absorbed in Viscous Flow”.

1. During which case will the power loss be maximum?
a) High viscosity oil
b) Low viscosity oil
c) High viscosity water
d) Low viscosity water
View Answer

Answer: a
Explanation: A highly viscous oil will offer greater resistance due to which the power loss is maximum. As we know, oil has a greater density than water. Thus, oil is more viscous than water and corresponds to a higher loss of power.

2. Angular speed of the shaft is________
a) 2πN/1000
b) 2πN/60
c) 2π/N
d) 2N/60
View Answer

Answer: b
Explanation: Angular speed is defined as the rate at which an object changes its angles. The angle can be measured in radians. Angular speed is a scalar quantity. It is measured within a given time period.

3. Tangential speed of the shaft is______
a) 2πN/1000
b) πDN/1000
c) πDN/60
d) 2πN/60
View Answer

Answer: c
Explanation: Tangential speed is defined as the distance travelled per unit time. It is a linear speed of something that moves around a circular path. Example of tangential speed is a point on the edge of a merry-go-round. The merry-go-round travels a greater distance in one complete rotation than the point near the centre.

4. Fluid does not offer resistance to change of__________
a) Temperature
b) Volume
c) Pressure
d) Shape
View Answer

Answer: d
Explanation: Shape is one of the most important factors for a fluid. The forces other than gravity that fall on the fluid affects the outcome. Thus, changing the shape of the fluid cannot be controlled.

5. If a fluid does not undergo any sort of resistance by displacement. What substance is it called?
a) Ideal fluid
b) Solid
c) Gas
d) Water
View Answer

Answer: a
Explanation: An ideal fluid is a fluid that has zero viscosity. It results in a flow called as inviscid flow. In this flow there is no existence of shear force and the viscosity vanishes.
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6. Why can’t mercury wet a glass?
a) Cohesion
b) Adhesion
c) Surface tension
d) Compressibility
View Answer

Answer: c
Explanation: Surface tension is an elastic tendency of a fluid. It results due to imbalance of intermolecular attractive forces. Any molecule at the surface of the liquid experiences a net inward force. Mercury having a higher density than water, cannot wet a glass.

7. What is the unit of power absorbed in a fluid?
a) Ampere
b) Volt/m
c) kgm2s-3
d) kg/m
View Answer

Answer: c
Explanation: Unit of power is a Watt. This is in accordance with the SI unit. The International system of units define it as 1 joule per second. Therefore, the SI base unit is kgm2s-3. It was named after James Watt.

8. One horse power is__________
a) 7460 W
b) 746 kW
c) 746 W
d) 0.746 W
View Answer

Answer: c
Explanation: Horse power is defined as the unit of foot-pound-second. Foot-pound-second(fps) is a unit in accordance with the English system. One horse power is equal to 550 fps/s. Thus, the power relation is 1HP= 746W.

Sanfoundry Global Education & Learning Series – Fluid Mechanics.


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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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