1. 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
Answer & Explanations
Answer: d
Explanation: 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.
2. The device used to measure the fluid pressure is _____________
a) Hygrometer
b) Calorimeter
c) Manometer
d) Thermometer
Answer & Explanations
Answer: c
Explanation: 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.
3. What type of liquids are measured using a manometer?
a) Heavy liquids
b) Medium Liquids
c) Light Liquids
d) Heavy and light liquids
Answer & Explanations
Answer: c
Explanation: 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.
4. 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
Answer & Explanations
Answer: c
Explanation: 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.
5. How do we measure the flow rate of liquid?
a) Coriolis method
b) Dead weight method
c) Conveyor method
d) Ionization method
Answer & Explanations
Answer: a
Explanation: 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.
6. What is the instrument used for the automatic control scheme during the fluid flow?
a) Rotameters
b) Pulley plates
c) Rotary Piston
d) Pilot Static Tube
Answer & Explanations
Answer: d
Explanation: 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.
7. 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
Answer & Explanations
Answer: c
Explanation: 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.
8. What is the viscosity of water at 30oC?
a) 80.1
b) 0 .801
c) 801
d) 0.081
Answer & Explanations
Answer: b
Explanation: 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.
9. If fluid is at rest in a container of a narrow mouth at a certain column height and same fluid is at rest at same column height in a container having broad mouth, will the pressure be different at certain depth from fluid surface.
a) Pressure will be same for both.
b) Pressure will be more for narrower mouth
c) Pressure will be less for narrower mouth
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: As per hydrostatic law, the pressure depends only on the height of water column and not its shape.
10. We can draw Mohr’s circle for a fluid at rest.
a) True
b) false
Answer & Explanations
Answer: b
Explanation: Mohr’s circle is used to denote shear stress distribution. For fluid at rest, there is no shear stress. Hence, we cannot draw Mohr’s circle for fluid at rest.
11. Pressure intensity or force due to pressure gradient for fluid at rest is considered as which kind of force?
a) Surface force
b) Body force
c) Force due to motion
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Pressure force is surface force.
12. Calculate the hydrostatic pressure for water moving with constant velocity at a depth of 5 m from the surface.
a) 49 kN/m2
b) 98 kN/m2
c) since fluid is in motion, we cannot analyse
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: If fluid is moving with uniform velocity we treat it analytically same as if fluid is at rest
p= ρgh.
13. Pressure distribution for fluid at rest takes into consideration pressure due to viscous force.
a) True
b) False
Answer & Explanations
Answer: b
Explanation: Viscous force term in pressure expression for fluid at rest is absent as their is no motion of liquid.
14. Barometer uses the principle of fluid at rest or pressure gradient for its pressure calculation.
a) True
b) False
Answer & Explanations
Answer: a
Explanation: Principle of Barometer is Hydrostatic law.
15. Why is large reservoir used in single column manometer?
a) In order to enhance the change in level of liquid in reservoir
b) In order to negate the effects of change in level due to pressure variation
c) In order to reduce the effect due to dynamic pressure variation due to motion
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: Single column manometer directly gives the pressure by measuring the height in the other limb and due to large cross sectional area of the reservoir, for any variation in pressure, the change can be neglected.
16. Manometers are the pressure measuring devices which use the principle of dynamic pressure to measure the pressure difference.
a) True
b) False
Answer & Explanations
Answer: b
Explanation: Manometers are the pressure measuring devices which use the principle of pressure due to static fluid (i.e the column height) to measure the pressure difference.
17. The distance moved by liquid will be more in which type of manometer?
a) Inclined Single coloumn manometer
b) Vertical Single coloumn manometer
c) Horizontal Single coloumn manometer
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: The distance moved by liquid will be more in Inclined Single column manometer due to its inclination.
18. Differential manometer gives the pressure reading with respect to atmospheric pressure.
a) True
b) False
Answer & Explanations
Answer: b
Explanation: Differential manometer gives the pressure difference between the fluid flowing in two pipes with respect to each other.
19. Which device is popularly used for measuring difference of low pressure?
a) Inverted U-tube Differential Manometer
b) U-tube Differential Manometer
c) Inclined Single column manometer
d) Vertical Single column manometer
Answer & Explanations
Answer: a
Explanation: Inverted U-tube Differential Manometer has lighter manometric fluid, Hence it is used for measuring the low pressure difference.
20. In the inverted U-tube Differential manometer, how is the specific gravity of manometric fluid used relative to the fluid flowing in the pipes
a) Specific gravity is more than that of fluid flowing in pipes
b) Specific gravity is less than that of fluid flowing in pipes
c) Specific gravity is equal to that of fluid flowing in pipes
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: In the inverted U-tube Differential manometer, specific gravity of manometric fluid used is less than relative to the fluid flowing in the pipes as the manonmetric fluid is at the top.
21. Pressure variation for compressible fluid is maximum for which kind of process?
a) Isothermal
b) Adiabatic
c) Quasi Static
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Due to constant temperature, pressure variation for compressible fluid is maximum for isothermal process.
22. Why can’t the density be assumed as constant for compressible fluids?
a) It shows variation with temperature and pressure
b) It remains constant with temperature and pressure
c) It becomes almost constant at very high temperature
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Volume and hence density changes with change in temperature and pressure.
23.What is the variation observed in temperature in atmosphere with respect to elevation?
a) It goes on decreasing with height
b) It goes on increasing with height
c) It first increases then decreases
d) It first decreases then increases
Answer & Explanations
Answer: d
Explanation: It goes on decreasing first and shows increase after 32000 m.
24. As we go upwards, at height there is slight decrease in pressure variation.
a) True
b) False
Answer & Explanations
Answer: a
Explanation: There is slight decrease in pressure as value of g (acceleration due to gravity) decreases slightly as we go higher.
25. For dynamic fluid motion in a pipe, the pressure measurement cannot be carried out accurately by manometer.
a) True
b) False
Answer & Explanations
Answer: a
Explanation: For fluid moving with variable velocity, fluctuation in pressure is frequent and more in magnitude. Hence, we cannot use manometer.
26. A simple U tube manometer connected to a pipe in which liquid is flowing with uniform speed will give which kind of pressure?
a) Absolute Pressure
b) Vacuum Pressure
c) Gauge Pressure
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: A simple U tube manometer will give pressure with respect to atmosphere. Hence, it is gauge pressure.
27. 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
Answer & Explanations
Answer: a
Explanation: 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)].
28. 15 bar equals to __________ Pascals.
a) 105Pa
b) 1.5 x 106 Pa
c) 100 Pa
d) 1000 Pa
Answer & Explanations
Answer: b
Explanation: 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.
29. A Hydraulic press has a ram of 30 cm diameter and a plunger of of 2 cm diameter. It is used for lifting a weight of 35 kN. Find the force required at the plunger.
a) 233.3 kN
b) 311.1 kN
c) 466.6 kN
d) 155.5 kN
Answer & Explanations
Answer: d
Explanation: F/a=W/A
F=(35000*3.142*.02*.02)/(3.142*0.3*0.3)
=155.5 kN.
30. The pressure at a point in the fluid is 4.9 N/cm2. Find height when the fluid under consideration is in oil of specific gravity of 0.85.
a) 5.83 m
b) 11.66 m
c) 17.49 m
d) 8.74 m
Answer & Explanations
Answer: a
Explanation: Height=p/ρg
=48620/850*9.81
=5.83 m.
31. An open tank contains water upto a depth of 350 cm and above it an oil of specific gravity 0.65 for a depth of 2.5 m. Find the pressure intensity at the extreme bottom of the tank.
a) 5.027 N/cm2
b) 10.05 N/cm2
c) 2.51 N/cm2
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: p= (specific gravity of water* height of water + specific gravity of oil* height of oil) * 9.81
= 5.027 N/cm2.
32. The diameters of a small piston and a large piston of a hydraulic jack are 45 mm and 100 mm respectively. Force of 0.09 kN applied on smaller in size piston. Find load lifted by piston if smaller in size piston is 40 cm above the large piston. The density of fluid is 850 kg/m3
a) 60 N/cm2
b) 12 N/cm2
c) 30 N/cm2
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Pressure at bottom of tank =ρgh + F/a
=850*9.81*0.4 + 90/3.142*0.045*0.045
=60 N/cm2.
33. The right limb of a simple U-tube manometer containing mercury is open to the atmosphere while the lift limb is connected to a pipe in which a fluid of specific gravity 0.85 is flowing. The centre of the pipe is 14 cm below the level of mercury in the right limb.Evaluate the pressure of fluid flowing in the pipe if the difference of mercury level in the two limbs is 22 cm.
a) 2.86 N/cm2
b) 5.73 N/cm2
c) 1.43 N/cm2
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Pressure at centre of pipe + Pressure at depth 8 cm in left limb = Pressure at depth 22 cm in right limb
P = 13600×9.81×0.22 – 850×9.81×.08
= 2.86 N/cm2.
34. A single coloumn manometer is connected to a pipe containing a liquid of specific gravity 0.75. Find the pressure in the pipe if the area of reservoir is 250 times the area of tube for the manometer reading. The difference in mercury level is 40 cm. On the left limb the fluid is upto the height of 20 cm.
a) 10.42 N/cm2
b) 5.21 N/cm2
c) 2.60 N/cm2
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: Pressure = a/A height × (density of mercury × 9.81-density of fluid × 9.81)+ height in right limb × density of mercury × 9.81 – height in left limb × density of fluid × 9.81
= 5.21 N/cm2
{ Here a/A = 1/ 250}.
35. A Differential manometer is connected at the points A and Bat the centre of two pipes. The pipe A(left limb) contains a liquid of specific gravity = 1.5 while pipe B (right limb)contains a liquid of specific gravity 0.85. The pressure at A and B are .5 kgf/cm2 and 1.2 kgf/cm2 respectively. Find the difference in level of mercuru in the differential manometer. A is 2.5m above B and 5 m above the mercury in its own limb. B is 2.5 m above the mercury level in limb A.
a) 12.7 cm
b) 25.5 cm
c) 6.28 cm
d) 10.85 cm
Answer & Explanations
Answer: a
Explanation: Total pressure at the datum line in limb A = Total pressure at the datum line in limb B\
0.5*9.81*10000 + 5*9.81*1500 + h*9.81*13600 = 1.2*9.81*10000 + (h+2)*9.81*850
After solving,
h=12.7 cm.
36. An inverted differential manometer is connected to two pipes A and B which covey water. The fluid in manometer is oil of specific gravity 0.75. For the manometer readings, find the pressure difference between A and B. Datum in left limb is 40 cm above point A. Point B is 60 cm below datum line. Difference in level of fluid is 20 cm.
a) 1471 N/m2
b) 2943 N/m2
c) 735.75 N/m2
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Total pressure at the datum line in limb A = Total pressure at the datum line in limb B
Pressure difference between A and B = -0.4*9.81*100 + 0.2*9.81*750 + 0.4*9.81*1000
= 1471 N/m2.
37. If the atmospheric pressure at sea level is 7.5 N/cm2, determine the pressure at a height of 3000m assuming the pressure variation follows isothermal law. The density of air is given as 1.2 km/m3.
a) 4.68 N/cm2
b) 9.37 N/cm2
c) 2.34 N/cm2
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: pressure at any height Z = p*e-gZ/RT
=75000*e -9.81*3000*1.2/75000
= 4.68 N/cm2.
38. The barometric pressure at sea level is 760 mm of Mercury while that on a mountain top is 715 mm. If the density of air is assumed constant at 1.2 kg/m3 , what is the elevation of the mountain top?
a) 510 m
b) 1020 m
c) 255 m
d) 128 m
Answer & Explanations
Answer: a
Explanation: Gauge pressure at any height h = pressure at sea level – pressure at that height
h=(9.81*13600*0.76)-9.81*13600*0.715)/1.2*9.81
=510 m.
39. Calculate the pressure at a height of 6500m above the sea level if the atmospheric pressure is 10.145 N/cm2 and temperature is 25℃ assuming air is incompressible. Take density of air as 1.2 kg/m3. Neglect variation of g.
a) 4.98 N/cm2
b) 2.49 N/cm2
c) 1.24 N/cm2
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: Pressure= p – density of air*g*height
=101450-9.81*1.2*6500
= 2.49 N/cm2.
40. Calculate the pressure of air at a height of 3500m from sea level where pressure and temperature of air are 10 N/cm2 and 25℃ respectively. The temperature lapse rate is given as 0.0065 ℃ /m. Take density of air at sea level equal to 1.2 kg/m3.
a) 19.7 N/cm2
b) 9.85 N/cm2
c) 4.93 N/cm2
d) 6.24 N/cm2
Answer & Explanations
Answer: b
Explanation: pressure=p * (1-(k-1/k)*g*h*density/p)k/(k-1)
=9.85 N/cm2
Here, Lapse rate= -g/R*(k/k-1).
