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4

The water in a jet propelled boat is drawn through the openings facing the direction of motion of the boat. The efficiency of propulsion is given by

A. 2V/(vr - v)

B. 2V/(vr + v)

C. V/(vr - v)

D. V/(vr + v)

Correct Answer :

B. 2V/(vr + v)


Related Questions

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4

The ratio of the normal force of jet of water on a plate inclined at an angle of 30° as compared to that when the plate is normal to jet, is

A. 1/√2

B. 1/2

C. 1

D. √2

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4

Mechanical efficiency of a centrifugal pump is the ratio of

A. Energy available at the impeller to the energy supplied to the pump by the prime mover

B. Actual workdone by the pump to the energy supplied to the pump by the prime mover

C. Energy supplied to the pump to the energy available at the impeller

D. Manometric head to the energy supplied by the impeller per kN of water

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4

Power required to drive a centrifugal pump is directly proportional to ________ of its impeller.

A. Diameter

B. Square of diameter

C. Cube of diameter

D. Fourth power of diameter

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4

If the ratios of all the corresponding linear dimensions are equal, then the model and the prototype are said to have

A. Geometric similarity

B. Kinematic similarity

C. Dynamic similarity

D. None of these

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4

In centrifugal pumps, maximum efficiency is obtained when the blades are

A. Straight

B. Bent forward

C. Bent backward

D. Radial

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4

Medium specific speed of turbine implies it is

A. Propeller turbine

B. Francis turbine

C. Impulse turbine

D. Any one of the above

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4

Which place in hydraulic turbine is most susceptible for cavitations?

A. Inlet of draft rube

B. Blade inlet

C. Guide blade

D. Penstock

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4

The efficiency of jet propulsion for a ship with inlet orifices at right angles to the direction of motion of ship is given by

A. [2(Vr - v) v]/ Vr²

B. 2(Vr + v) v]/ Vr²

C. [(Vr - v) v]/ Vr

D. [(Vr + v) v]/ Vr

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4

The depth of the bucket for a Pelton wheel is generally ________ the diameter of jet.

A. Equal to

B. 1.2 times

C. 1.8 times

D. Double

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4

The function of guide vanes in a reaction turbine is to

A. Allow the water to enter the runner without shock

B. Allow the water to flow over them, without forming eddies

C. Allow the required quantity of water to enter the turbine

D. All of the above

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4

According to fan laws, for fans having constant wheel diameter, the pressure varies

A. Directly as fan speed

B. Square of fan speed

C. Cube of fan speed

D. Square root of fan speed

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4

Overall efficiency of a centrifugal pump is the ratio of

A. Energy available at the impeller to the energy supplied to the pump by the prime mover

B. Actual workdone by the pump to the energy supplied to the pump by the prime mover

C. Energy supplied to the pump to the energy available at the impeller

D. Manometric head to the energy supplied by the impeller per kN of water

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4

Braking jet in an impulse turbine is used

A. To break the jet of water

B. To bring the runner to rest in a short time

C. To change the direction of runner

D. None of these

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4

Puck up the wrong statement about centrifugal pump

A. Discharge a diameter

B. Head a speed²

C. Head a diameter

D. Power a speed⁴

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4

Which of the following statement is correct?

A. The centrifugal pump is suitable for large discharge and smaller heads.

B. The centrifugal pump requires less floor area and simple foundation as compared to reciprocating pump.

C. The efficiency of centrifugal pump is less as compared to reciprocating pump.

D. All of the above

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4

The centrifugal pump preferred for a specific speed between 80 to 160 r.p.m. is

A. Slow speed with radial flow at outlet

B. Medium speed with radial flow at outlet

C. High speed with radial flow at outlet

D. High speed with mixed flow at outlet

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4

Delivery head of a centrifugal pump is

A. Directly proportional to N

B. Inversely proportional to N

C. Directly proportional to N²

D. Inversely proportional to N²

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4

A hydraulic accumulator normally consists of

A. Two cylinders, two rams and a storage device

B. A cylinder and a ram

C. Two coaxial rams and two cylinders

D. A cylinder, a piston, storage tank and control valve

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4

Multistage centrifugal pumps are used to

A. Give high discharge

B. Produce high heads

C. Pump viscous fluids

D. All of these

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4

A double overhung Pelton wheel has

A. Two jets

B. Two runners

C. Four jets

D. Four runners

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4

Discharge of a centrifugal pump is (where N = Speed of the pump impeller)

A. Directly proportional to N

B. Inversely proportional to N

C. Directly proportional to N²

D. Inversely proportional to N²

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4

According to fan laws, for fans having constant wheel diameter, the air or gas capacity varies

A. Directly as fan speed

B. Square of fan speed

C. Cube of fan speed

D. Square root of fan speed

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4

The ratio of quantity of liquid discharged per second from the pump to the quantity of liquid passing per second through the impeller is known as

A. Manometric efficiency

B. Mechanical efficiency

C. Overall efficiency

D. Volumetric efficiency

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4

The working of which of the following hydraulic units is based on Pascal's law?

A. Air lift pump

B. Jet pump

C. Hydraulic coupling

D. Hydraulic press

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4

The type of centrifugal pump preferred for a specific speed of 20 r.p.m. is

A. Slow speed pump with radial flow at outlet

B. Medium speed pump with radial flow at outlet

C. High speed pump with radial flow at outlet

D. High speed pump with axial flow at outlet

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4

The hydraulic efficiency of an impulse turbine is the

A. Ratio of the actual power produced by the turbine to the energy actually supplied by the turbine

B. Ratio of the actual work available at the turbine to the energy imparted to the wheel

C. Ratio of the work done on the wheel to the energy of the jet

D. None of the above

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4

The maximum efficiency of jet propulsion of a ship with inlet orifices at right angles to the direction of motion of ship, is

A. 40 %

B. 50 %

C. 60 %

D. 80 %

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4

Francis turbine is best suited for

A. Medium head application from 24 to 180 m

B. Low head installation up to 30 m

C. High head installation above 180 m

D. All types of heads

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4

If a pump is handling water and is discharging a certain flow Q at a constant total dynamic head requiring a definite B.H.P., the same pump when handling a liquid of specific gravity 0.75 and viscosity nearly same as of water, the horse power required will be

A. Same

B. 0.75 B.H.P.

C. B.H.P./0.75

D. 1.5 B.H.P.

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4

The undershot water wheels are those in which

A. The wheel runs entirely by the weight of water

B. The wheel runs entirely by the impulse of water

C. The wheel runs partly by the weight of water and partly by the impulse of water

D. None of the above