MCQOPTIONS
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MCQOPTIONS
This section includes 238 Mcqs, each offering curated multiple-choice questions to sharpen your Fluid Mechanics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Medium specific speed of a pump implies that it is _____. |
| A. | Centrifugal pump |
| B. | Mixed flow pump |
| C. | Axial flow pump |
| D. | Axial flow pump or centrifugal pump |
| Answer» C. Axial flow pump | |
| 2. |
Draft tube is used in reaction turbine to |
| A. | Pass water downstream without eddies formation |
| B. | Convert the kinetic energy into pressure energy by the gradual expansion of the flow cross-section |
| C. | Provide safety to the turbine |
| D. | Prevent water splitting |
| Answer» C. Provide safety to the turbine | |
| 3. |
If mechanical efficiency of a Pelton Turbine is 80% and its hydraulic efficiency is 85%, its overall efficiency will be: |
| A. | 50% |
| B. | 75% |
| C. | 68% |
| D. | 72% |
| Answer» D. 72% | |
| 4. |
In a draft tube at the exit of a turbine |
| A. | the kinetic energy increases |
| B. | the flow is generally laminar |
| C. | sand particles are prevented from entering the turbine |
| D. | the cross-sectional area increases in flow direction |
| Answer» E. | |
| 5. |
Kaplan water turbine is commonly used when the flow through its runner is |
| A. | axial and the head available is more than 100 m |
| B. | axial and the head available is less than 10 m |
| C. | radial and the head available is more than 100 m |
| D. | mixed and the head available is about 50 m |
| Answer» C. radial and the head available is more than 100 m | |
| 6. |
A Pelton wheel operates with a speed of 600 rpm speed ratio of 0.44 and a net head of 300 m. The diameter of the wheel is |
| A. | 0.82 m |
| B. | 1.07 m |
| C. | 1.51 m |
| D. | 2.14 m |
| Answer» C. 1.51 m | |
| 7. |
A fast centrifugal pump impeller has which of the following? |
| A. | Radial blades |
| B. | Backward facing blades |
| C. | Propeller type blades |
| D. | Forward facing blades |
| Answer» C. Propeller type blades | |
| 8. |
If in a pump, the discharge is halved, then assuming that the speed remains unchanged, what would be the ratio of the heads \(\frac{{{H_1}}}{{{H_2}}}\) ? |
| A. | \(\sqrt {\frac{1}{3}}\) |
| B. | \(\sqrt {\frac{2}{3}}\) |
| C. | \(\sqrt[3]{{4}}\) |
| D. | \(\sqrt[3]{{0.5}}\) |
| Answer» D. \(\sqrt[3]{{0.5}}\) | |
| 9. |
Jet pumps are often used in process industry for their |
| A. | Large capacity |
| B. | High efficiency |
| C. | Capacity to transport gases, liquids and mixtures of both |
| D. | None of the above |
| Answer» D. None of the above | |
| 10. |
Double hemispherical buckets are used in: |
| A. | bulb turbine |
| B. | kaplan turbine |
| C. | pelton wheel |
| D. | propeller turbine |
| Answer» D. propeller turbine | |
| 11. |
A reaction turbine has a discharge 30m3/s passing through it under a net head of 10 m. If the overall efficiency is 0.866, the power developed in kW is |
| A. | 3400 |
| B. | 3450 |
| C. | 2940 |
| D. | 2500 |
| Answer» E. | |
| 12. |
If the net positive section head (NPSH) for the pump is not satisfied, then |
| A. | no flow take place |
| B. | efficiency will be low |
| C. | cavitation will be formed |
| D. | pump will not start |
| Answer» D. pump will not start | |
| 13. |
Low specific speed of a turbine implies it is |
| A. | Propeller turbine |
| B. | Francis turbine |
| C. | Impulse turbine |
| D. | Kaplan turbine |
| Answer» D. Kaplan turbine | |
| 14. |
For high head, suitable turbine is _________ |
| A. | Pelton |
| B. | Francis |
| C. | Kaplan |
| D. | None of the above |
| Answer» B. Francis | |
| 15. |
A draft tube converts |
| A. | Pressure energy into kinetic eenrgy |
| B. | Velocity head into potential head |
| C. | Potential head into pressure head |
| D. | Kinetic energy into pressure energy |
| Answer» E. | |
| 16. |
A pump is defined as a device which converts |
| A. | Hydraulic energy into mechanical energy |
| B. | Mechanical energy into hydraulic energy |
| C. | Kinetic energy into mechanical energy |
| D. | None of the above |
| Answer» C. Kinetic energy into mechanical energy | |
| 17. |
Cavitation in the pump occurs when |
| A. | Vapor pressure of liquid is greater than local pressure of liquid inside the pump |
| B. | Vapor pressure of liquid is lower than local pressure of liquid inside the pump |
| C. | Vapor pressure of liquid is lower than that of atmospheric pressure |
| D. | local pressure of liquid inside the pump is greater than atmospheric pressure |
| Answer» B. Vapor pressure of liquid is lower than local pressure of liquid inside the pump | |
| 18. |
During stroke of a reciprocating pump, the separation may take place_________ |
| A. | at the end of suction stroke |
| B. | in the middle of suction stroke |
| C. | at the beginning of suction stroke |
| D. | None of the above |
| Answer» D. None of the above | |
| 19. |
A centrifugal pump delivers 1000 litres per minute at 2000 RPM against total head of 50 mts, and requires 32 BHP for its operation. If speed is reduced to 1000 RPM, the discharge and head developed will be |
| A. | 500 l/min and 25 mtr |
| B. | 500 l/min and 12.5 mtr |
| C. | 250 l/min and 12.5 mtr |
| D. | 250 l/min and 25 mtr |
| Answer» C. 250 l/min and 12.5 mtr | |
| 20. |
Pick up the incorrect statement for centrifugal pumps |
| A. | Discharge ∝ diameter |
| B. | Head ∝ (speed)2 |
| C. | Head ∝ (diameter)2 |
| D. | Discharge ∝ speed |
| Answer» B. Head ∝ (speed)2 | |
| 21. |
For small discharge at high pressure following pump is preferred: |
| A. | Mixed flow |
| B. | Reciprocating |
| C. | Axial flow |
| D. | Centrifugal |
| Answer» C. Axial flow | |
| 22. |
Match the items in columns I and II.Column IColumn IIP. Centrifugal compressor1. Axial flowQ. Centrifugal pump2. SurgingR. Pelton wheel3. PrimingS. Kaplan turbine4. Pure impulse |
| A. | P – 2, Q – 3, R – 4, S – 1 |
| B. | P – 2, Q – 3, R – 1, S – 4 |
| C. | P – 3, Q – 4, R – 1, S – 2 |
| D. | P – 1, Q – 2, R – 3, S – 4 |
| Answer» B. P – 2, Q – 3, R – 1, S – 4 | |
| 23. |
Jet ratio (m) is defined as the ratio of |
| A. | Diameter of the jet of water to diameter of the Pelton wheel |
| B. | Velocity of the vane to velocity of the jet of water |
| C. | Velocity of flow to velocity of the jet of water |
| D. | Diameter of Pelton wheel to the diameter of the jet of water |
| Answer» E. | |
| 24. |
A centrifugal pump driven by a directly coupled 3 kW motor of 1450 rpm speed, is proposed to be connected to a motor of 2900 rpm speed. The power of the motor should be |
| A. | 6 kW |
| B. | 12 kW |
| C. | 18 kW |
| D. | 24 kW |
| Answer» E. | |
| 25. |
For the operating point of the pump, a system characteristic between the head required ‘H’ and the discharge to be maintained ‘Q’ is generally expressed as |
| A. | Linear equation |
| B. | Parabolic equation |
| C. | Exponential equation |
| D. | Cubic equation |
| Answer» C. Exponential equation | |
| 26. |
A single acting reciprocating pump, running at 60 rpm, delivers 0.01 m3/sec of water. The area of the piston is 0.05 m2 and stroke length is 40 cm. Then theoretical discharge of the pump will be, |
| A. | 0.015 m3/sec |
| B. | 0.02 m3/sec |
| C. | 0.025 m3/sec |
| D. | 0.03 m3/sec |
| Answer» C. 0.025 m3/sec | |
| 27. |
A centrifugal pump having an impeller diameter of 127 mm, delivers a power of 12 hp. If the impeller diameter is changed to 254 mm, what is the power, if other parameters are kept constant? |
| A. | 48 hp |
| B. | 192 hp |
| C. | 24 hp |
| D. | 384 hp |
| Answer» E. | |
| 28. |
A Pelton wheel is running at 2000 r.p.m. and it develops 68.67 kW shaft power. The discharge through a nozzle is 0.02 m3/s and the net head on the Pelton wheel is 500 m. The overall efficiency of the Pelton wheel is |
| A. | 0.45 |
| B. | 0.5 |
| C. | 0.7 |
| D. | 0.9 |
| Answer» D. 0.9 | |
| 29. |
In a simple impulse turbine, the nozzle angle at the entrance is 30°. What will be the blade-speed ratio for maximum diagram efficiency? |
| A. | 0.433 |
| B. | 0.25 |
| C. | 0.5 |
| D. | 0.75 |
| Answer» B. 0.25 | |
| 30. |
In an inward flow reaction turbine ________. |
| A. | The water flows parallel to the axis of the wheel |
| B. | The water enters the centre of the wheel and there flows towards the outer periphery of the wheel |
| C. | The water enters the wheel at the outer periphery and then flows towards the centre of the wheel |
| D. | The flow of water is partly radial and partly axial |
| Answer» D. The flow of water is partly radial and partly axial | |
| 31. |
Centrifugal pumps dealing with muds have an impeller of the type |
| A. | Open |
| B. | Double suction |
| C. | One-side shrouded |
| D. | Two-sides shrouded |
| Answer» B. Double suction | |
| 32. |
Backward curved vanes are used in: |
| A. | axial flow pump |
| B. | vane pump |
| C. | reciprocating pump |
| D. | centrifugal pump |
| Answer» E. | |
| 33. |
A turbine develops 9000 kW when running at 100 rpm. Head on the turbine is 30 m. If the head on the turbine is reduced to 18 m, speed of the turbine under 18 m is: |
| A. | 77 rpm |
| B. | 18 rpm |
| C. | 180 rpm |
| D. | 30 rpm |
| Answer» B. 18 rpm | |
| 34. |
Any change in load is adjusted by adjusting the following parameter on the turbine |
| A. | Net head |
| B. | Absolute velocity |
| C. | Blade velocity |
| D. | Flow |
| Answer» E. | |
| 35. |
In order to have maximum power from a Pelton turbine, the bucket speed must be |
| A. | Equal to the jet speed |
| B. | Equal to half the jet speed |
| C. | Equal to twice the jet speed |
| D. | Independent of the jet speed |
| Answer» C. Equal to twice the jet speed | |
| 36. |
For low heads only, these turbines are used |
| A. | Kaplan turbine |
| B. | Francis turbine |
| C. | Pelton wheels |
| D. | Deriaz turbine |
| Answer» B. Francis turbine | |
| 37. |
A double-acting reciprocating pump with 50 rpm speed and a piston having 400 mm stroke length and 0.03 m2 cross-sectional area will have a theoretical fluid flow of |
| A. | 0.01 m3/s |
| B. | 0.02 m3/s |
| C. | 0.6 m3/s |
| D. | 10 m3/s |
| Answer» C. 0.6 m3/s | |
| 38. |
A draft tube is used with _____. |
| A. | Impulse turbine |
| B. | Pelton wheel turbine |
| C. | Reaction turbines |
| D. | Axial turbine pumps |
| Answer» D. Axial turbine pumps | |
| 39. |
Formation and collapse of vapour bubbles are believed to be the root cause for cavitation’s in hydraulic turbines. Most favourable condition for the formation of bubbles is set in the turbines at |
| A. | Penstock/Nozzle |
| B. | Guide vanes/Inlet of the runner |
| C. | Vanes receiving impact of jet |
| D. | Outlet of the runner/Entrance of the draft tube |
| Answer» E. | |
| 40. |
Pelton wheel is choosen for a head of |
| A. | 15 m |
| B. | 30 m |
| C. | 100 m |
| D. | 40 m |
| Answer» D. 40 m | |
| 41. |
A jet of water issues from a nozzle with a velocity of 20 m/s and it impinges normally on a flat plate moving away from it at 10 m/s. If the cross-sectional area of the jet is 0.01 m2 and the density of water is taken as 1000 kg/m3, then the force developed on the plate will be |
| A. | 100 N |
| B. | 200 N |
| C. | 1000 N |
| D. | 2000 N |
| Answer» D. 2000 N | |
| 42. |
Consider the following data from a test on the Pelton wheel:Head at the base of the nozzle = 32 mDischarge of the nozzle = 0.18 m3/sArea of the jet = 7500 mm2Power available at the shaft = 44 kWMechanical efficiency = 94%The power lost in the nozzle will be nearly |
| A. | 3.9 kW |
| B. | 4.7 kW |
| C. | 3.5 kW |
| D. | 2.3 kW |
| Answer» D. 2.3 kW | |
| 43. |
Kaplan turbine is a type of which of the following? |
| A. | Reaction turbine |
| B. | None of the above |
| C. | Propeller turbine |
| D. | Francis turbine |
| Answer» B. None of the above | |
| 44. |
An impulse hydraulic turbine: |
| A. | Always operates while submerged completely in water |
| B. | Makes use of a draft tube |
| C. | Converts pressure head into velocity head throughout the vane |
| D. | Operates by initial complete conversion of potential energy to kinetic energy |
| Answer» E. | |
| 45. |
A necessary precaution in selection of pumps for parallel operations is that |
| A. | H-Q characteristics of both should be identical |
| B. | Both pumps should be centrifugal type |
| C. | Both pumps should be identical |
| D. | There should not be change from positive to negative slope in H-Q curve |
| Answer» B. Both pumps should be centrifugal type | |
| 46. |
A 15 kW centrifugal pump working at 75% efficiency is pumping a liquid of unit weight 10000 N/cum through an additional head of 10 m, what is the discharge in cum/s? |
| A. | 0.15 |
| B. | 0.1125 |
| C. | 0.1 |
| D. | 0.125 |
| E. | 0.18 |
| Answer» C. 0.1 | |
| 47. |
A turbine develops 500 kW power under a head of 100 m at 200 rpm. What would be its normal speed under a head of 81 m? |
| A. | 100 rpm |
| B. | 180 rpm |
| C. | 1800 rpm |
| D. | 162 rpm |
| Answer» C. 1800 rpm | |
| 48. |
In the main characteristic curve of a centrifugal pump, the power is proportional to |
| A. | speed |
| B. | square of speed |
| C. | fourth power of speed |
| D. | cube of speed |
| Answer» E. | |
| 49. |
Multi-stage centrifugal pumps are used to: |
| A. | give high discharge |
| B. | produce high heads |
| C. | pump viscous fluids |
| D. | all of these |
| Answer» C. pump viscous fluids | |
| 50. |
Cavitation in a pump is associated with _________ pressure. |
| A. | atmospheric |
| B. | critical |
| C. | vapor |
| D. | None of these |
| Answer» D. None of these | |