Fluid Mechanics Multiple Choice Questions on “Fluid Pressure”.
1. What is the pressure in Pascals at a depth of 1m below the water surface?
a) 98100 Pa
b) 980 Pa
c) 98 Pa
d) 1 Pa
Clarification: It’s the summation of weights on top of the water surface. In this case, it is the weight of the atmosphere and water above 1m. [Formula: P (depth) = Patm +(density of water*gravitational constant*depth)].
2. 15 bar equals to __________ Pascals.
b) 1.5 x 106 Pa
c) 100 Pa
d) 1000 Pa
Clarification: Bar is a metric unit of pressure, but it does not fall under the SI units. One bar is exactly equal to a 100,000 Pascals. This value is taken from the atmospheric pressure on the earth at sea level.
3. The pressure at any given point of a non-moving fluid is called the ____________
a) Gauge Pressure
b) Atmospheric Pressure
c) Differential Pressure
d) Hydrostatic Pressure
Clarification: Hydrostatic pressure varies with the increase in depth. Hydrostatic pressure is measured from the surface of the fluid because of the increasing weight of the fluid. The fluid exerts a downward force from the surface of water thus making it a non-moving fluid.
4. The device used to measure the fluid pressure is _____________
Clarification: Manometer is the most preferred measuring device as the pressure is measured by difference in the column heights of the manometer. It is expressed in terms of inches or centimeters of fluid making it easier for the conversion process.
5. What type of liquids are measured using a manometer?
a) Heavy liquids
b) Medium Liquids
c) Light Liquids
d) Heavy and light liquids
Clarification: Measurement of liquid in a manometer takes place through differential pressures by balancing the weight. Thus, it is easier for the manometer to measure liquids of lesser density than the heavier ones. Example of a light liquid is Water.
6. Which among these devices are the best suited for the measurement of high pressure liquids with high accuracy?
a) Dead Weight Gauge
b) Vacuum Gauge
c) Manganin wire pressure
d) Ionization Gauge
Clarification: Manganin wire is the most suitable measurement device for high pressure liquids. It has a high stability and durability on a long term basis. It also has a high hydrostatic pressure sensitivity and low strain sensitivity.
7. How do we measure the flow rate of liquid?
a) Coriolis method
b) Dead weight method
c) Conveyor method
d) Ionization method
Clarification: Coriolis concept of measurement of fluid takes place through the rotation with the reference frame. It is an application of the Newton’s Law. The device continuously records, regulates and feeds large volume of bulk materials.
8. What is the instrument used for the automatic control scheme during the fluid flow?
b) Pulley plates
c) Rotary Piston
d) Pilot Static Tube
Clarification: Pilot static tube is a system that uses an automatic control scheme to detect pressure. It has several holes connected to one side of the device. These outside holes are called as a pressure transducer, which controls the automatic scheme during fluid flow.
9. Define Viscosity?
a) Resistance to flow of an object
b) Resistance to flow of air
c) Resistance to flow of fluid
d) Resistance to flow of heat
Clarification: Viscosity is developed due to the relative motion between two surfaces of fluids at different velocities. It happens due to the shear stress developed on the surface of the fluid.
10. What is the viscosity of water at 30oC?
b) 0 .801
Clarification: A graph is plotted with temperature in the x-axis and dynamic viscosity in the y-axis. With the increase in pressure the viscosity decreases. It corresponds to an informal concept of thickness.