Question Bank for Railways NTPC (Technical Ability) Instrument Mechanical Instrument Mechanical

List-I		List-II
A.	Head race	1.	Channel, tunnel or pipes through which water is carried from reservoir to the turbine
B.	Tail race	2.	Reservoir water level
C.	Penstock	3.	Diverging tube discharging water from the turbine to the atmosphere
D.	Draft tube	4.	The level at which water is discharged a atmospheric pressure

Codes:

A)

A\[\to \]1, B\[\to \]3, C\[\to \]2, D\[\to \]4

B)

A\[\to \]2, B\[\to \]4, C\[\to \]1, D\[\to \]3

C)

A\[\to \]1, B\[\to \]4, C\[\to \]2, D\[\to \]3

D)

A\[\to \]2, B\[\to \]3, C\[\to \]1, D\[\to \]4

View Solution

7)

Consider the following statements in respect of centrifugal pumps:

1. Head developed is proportional to the square of the speed of rotation.

2. Backward curved bladed impellers arc generally used in centrifugal pumps.

3. These pumps generally do not require priming.

4. Multistage pumps would give higher discharge proportional to the number of stages. Which of these statements are correct?

A)

1 and 2

B)

2 and 3

C)

3 and 4

D)

1 and 4

View Solution

8)

The relationship between overall efficiency \[({{\eta }_{0}})\], mechanical efficiency \[{{\eta }_{mech}}\], and hydraulic efficiency \[({{\eta }_{hyd}})\] of a turbine is:

A)

\[{{\eta }_{0}}\,=\,{{h}_{mech}}\,\times \,{{\eta }_{hyd}}\]

B)

\[{{\eta }_{0}}\,=\,{{h}_{mech}}\,/\,{{\eta }_{hyd}}\]

C)

\[{{\eta }_{0}}\,=\,{{\eta }_{hyd}}\,/\,{{\eta }_{mech}}\]

D)

\[{{\eta }_{0}}\,=\,{{\eta }_{mech}}\,-\,{{\eta }_{hyd}}\]

View Solution

9)

Which one of the following correctly expresses the specific speed of a turbine and a pump, respectively?

A)

\[\frac{N\sqrt{Q}}{{{H}^{3/4}}},\frac{N\sqrt{P}}{{{H}^{5/4}}}\]

B)

\[\frac{N\sqrt{P}}{{{H}^{3/4}}},\frac{N\sqrt{Q}}{{{H}^{5/4}}}\]

C)

\[\frac{N\sqrt{P}}{{{H}^{5/4}}},\frac{N\sqrt{Q}}{{{H}^{3/4}}}\]

D)

\[\frac{N\sqrt{P}}{{{H}^{7/4}}},\frac{N\sqrt{Q}}{{{H}^{3/4}}}\]

View Solution

10)

Consider the following statements:

In the thermoelectric refrigeration, the coefficient of performance is a function of:

1. Electrical conductivity of materials.

2. Peltier coefficient

3. See beck coefficient

4. Temperature at cold and hot functions

5. Thermal conductivity of materials.

Of these statements:

A)

1, 3, 4 and 5 are correct

B)

1, 2, 3 and 5 correct

C)

1, 2, 4 and 5 correct

D)

2, 3, 4 and 5 correct

View Solution

11)

Which one of the following is not correct regarding both Kaplan and propeller turbines?

A)

The runner is axial

B)

The blades are wing type

C)

There are four to eight blades

D)

The blades can he adjusted.

View Solution

12)

Based on the direction of flow, which one of the following turbines is different from the other three?

A)

Pelton turbine

B)

Kaplan turbine

C)

Dc Laval turbine

D)

Parson's turbine

View Solution

13)

Which one of the following is an example of a pure (100%) reaction machine?

A)

Pelton wheel

B)

Francis turbine

C)

Modern gas turbine

D)

Lawn sprinkler

View Solution

14)

Consider the following statements:

1. A reverse jet protects Pelton turbine from over speeding.

2. Runner blades of Francis turbine are adjustable.

3. Draft tube is used invariably in all reaction turbine installations.

4. Surge tank is a protective device on penstock. Of these statements:

A)

1 and 2 are correct

B)

2 and 3 are correct

C)

3 and 4 are correct

D)

1 and 4 are correct.

View Solution

15)

Unit power \[{{P}_{1}}\] is given by the expression:

A)

\[{{P}_{1}}=\frac{p}{\sqrt{H}}\]

B)

\[{{P}_{1}}=\frac{p}{{{H}^{3/2}}}\]

C)

\[{{P}_{1}}=\frac{p}{{{H}^{3/4}}}\]

D)

\[{{P}_{1}}=\frac{p}{{{H}^{3/5}}}\]

View Solution

16)

For discharge 'Q' the specific speed of a pump is\['{{N}_{s}}'.\] For half discharge with the same head, the specific speed will be:

A)

\[{{N}_{s}}\]

B)

\[\sqrt{2}{{N}_{s}}\]

C)

\[\frac{{{N}_{s}}}{\sqrt{2}}{{N}_{s}}\]

D)

\[2{{N}_{s}}.\]

View Solution

17)

Which one of the following statements regarding ammonia absorption system is correct?

A)

A function of the temperature and pressure of the solution

B)

A function of the pressure of the solution irrespective of the temperature

C)

A function of the temperature of the solution alone

D)

Independent of the temperature and pressure of the solution

View Solution

18)

For an impulse turbine with exit angle '\[\phi \]', the maximum hydraulic efficiency is:

A)

\[\left( 1-\frac{\cos \phi }{2} \right)\]

B)

\[\left( \frac{1}{2}+\cos \phi \right)\]

C)

\[\left( \frac{1+\cos \phi }{2} \right)\]

D)

\[\left( \frac{1-\cos \phi }{2} \right)\]

View Solution

19)

The location of a surge tank in a high head hydraulic power plant would be:

A)

Nearer to the dam

B)

At the powerhouse

C)

Nearest to the powerhouse

D)

Immaterial

View Solution

20)

Match List-1 with List-11 and select the correct answer using the codes given below the lists:

List-I (Water Turbines)		List-II (Application)
A.	Pelton	1.	High head and low discharge
B.	Francis	2.	High head and high discharge
C.	Kaplan	3.	Medium head and medium discharge
		4.	Low head and high discharge

Codes:

A)

A\[\to \]1, B\[\to \]3, C\[\to \]2

B)

A\[\to \]1, B\[\to \]3, C\[\to \]4

C)

A\[\to \]2, B\[\to \]4, C\[\to \]3

D)

A\[\to \]3, B\[\to \]2, C\[\to \]4

View Solution

21)

Which one of the following helps in avoiding cavitation in centrifugal pumps?

A)

Low suction pressure

B)

High delivery pressure

C)

Low delivery pressure

D)

High suction pressure

View Solution

22)

Consider the following statements with regard to the specific speeds of different types of

1. High specific speed implies that it is a Pelton wheel

2. Medium specific speed implies that it is an axial flow turbine

3. Low specific speed implies that it is a Francis turbine

4. Which of these statements given above is/are correct?

A)

1 only

B)

2 only

C)

3 only

D)

None

View Solution

23)

Which one of the following is the purpose of a surge tank in a Pelton turbine station?

A)

It acts as a temporary storage during load changes,

B)

It prevents hydraulic jump

C)

It prevents surges at the transformer

D)

It prevents water hammer due to sudden reduction in load.

View Solution

24)

Match List-I (Type of Turbine) with List-II (Specific Speed) and select the correct answer using the code given below the lists:

List-I (Type of Turbine)		List-II (Specific Speed)
A.	Pelton	1.	0.1
B.	Francis	2.	3.0
C.	Propeller	3.	4.0
D.	Kaplan	5.	1.0

Codes:

A)

A\[\to \]1, B\[\to \]4, C\[\to \]2, D\[\to \]3

B)

A\[\to \]3, B\[\to \]2, C\[\to \]4, D\[\to \]1

C)

A\[\to \]1, B\[\to \]2, C\[\to \]4, D\[\to \]3

D)

A\[\to \]3, B\[\to \]4, C\[\to \]2, D\[\to \]1

View Solution

25)

Consider the following statements: In hydraulic power plants

1. Pelton turbines are used for high heads.

2. Kaplan turbines are used for medium heads.

3. Francis turbines are used for low heads. Which of the above statements is/are correct?

A)

1 only

B)

2 only

C)

3 only

D)

1, 2 and 3

View Solution

26)

The speed ratio for Pelton wheel varies from:

A)

\[0.45\,-\,0.50\]

B)

\[0.6\,-\,0.7\]

C)

\[0.30\,-\,0.40\]

D)

\[0.8\,-\,0.9\]

View Solution

27)

Match List-I with List-II and select the correct answer using the codes given below the lists:

List-I		List-II
A.	Specific speed of pump	1.	\[\left( \frac{N\sqrt{Q}}{{{H}^{3/4}}} \right)\]
B.	Low specific speed of turbine.	2.	Screw pump
C.	Pumping viscous oil	3.	Reaction turbine
D.	Draft tube	4.	Turbine Pump
		5.	Very high specific speed
		6.	\[\left( \frac{N\sqrt{P}}{{{H}^{5/4}}} \right)\]
		7.	Impulse turbine

Codes:

A)

A\[\to \]1, B\[\to \]3, C\[\to \]2, D\[\to \]5

B)

A\[\to \]6, B\[\to \]7, C\[\to \]4, D\[\to \]3

C)

A\[\to \]1, B\[\to \]7, C\[\to \]2, D\[\to \]3

D)

A\[\to \]6, B\[\to \]3, C\[\to \]4, D\[\to \]5

View Solution

28)

Match List-I with List-II and select the correct answer using the codes given below the lists:

List-I		List-II
A.	Draft tube	1.	Impulse turbine
B.	Surging	2.	Reciprocating pump
C.	Air Vessel	3.	Reaction turbine
D.	Nozzle	4.	Centrifugal pump

Codes:

A)

A\[\to \]1, B\[\to \]2, C\[\to \]4, D\[\to \]3

B)

A\[\to \]3, B\[\to \]4, C\[\to \]2, D\[\to \]1

C)

A\[\to \]1, B\[\to \]4, C\[\to \]2, D\[\to \]3

D)

A\[\to \]3, B\[\to \]2, C\[\to \]4, D\[\to \]1

View Solution

29)

A centrifugal pump was manufactured to couple directly to a 15 HP. electric motor running at 1950 rpm delivering 50 liters per minute against a total head of 20 m. It is desired to replace the pump. The head developed by pump is likely to be:

A)

41.4 m

B)

29.6 m

C)

20 m

D)

9.5 m

View Solution

30)

Which of the following statements are false regarding the relation Specific speed. \[{{N}_{s}}\left( \frac{N\sqrt{Q}}{{{H}^{5/4}}} \right)\]

A)

The relation is valid for both impulse as well as reaction turbines

B)

The value of specific speed depends on the system of units

C)

The value of specific speed for pelton wheel will be lower than that for Kaplan turbine for any system of units

D)

The dimensions of specific speed are: \[(FLT{{\,}^{-\,1}})\]

View Solution

31)

Air vessel is used in a reciprocating pump to obtain:

A)

Reduction of suction head

B)

Rise in delivery head

C)

Continuous supply of water at uniform rate

D)

Increase in supply of water

View Solution

32)

Hydraulic transmission through fluid coupling is suitable for:

A)

Unsteady operation and increasing torque

B)

Unsteady operation and increasing speed

C)

Unsteady operation and low starting torque

D)

Increasing torque and low starting load

View Solution

33)

Match the following:

List-I		List-II
A.	Wicket gates	1.	Gradually converts the velocity head to pressure head
B.	Volute tube	2.	Pressure head recovery
C.	Draft tube	3.	High value of N and N
D.	Axial flow	4.	Adjustable by governor pumps according to head

Codes:

A)

A\[\to \]4, B\[\to \]1, C\[\to \]2, D\[\to \]3

B)

A\[\to \]1, B\[\to \]3, C\[\to \]2, D\[\to \]4

C)

A\[\to \]2, B\[\to \]3, C\[\to \]4, D\[\to \]1

D)

A\[\to \]2, B\[\to \]3, C\[\to \]1, D\[\to \]4

View Solution

34)

Chances of occurrence of cavitation are high if the:

A)

Local pressure becomes very high

B)

Local temperature becomes low

C)

Thoma cavitation parameter exceeds a certain limit

D)

Local pressure falls below the vapour pressure.

View Solution

35)

The specific speed of a hydraulic pump is the Speed of geometrically similar pump working against a unit head and:

A)

Delivering unit quantity of water

B)

Consuming unit power

C)

Having unit velocity of flow

D)

Having unit radial velocity

View Solution

36)

In the statement, "in a reaction turbine installation, the head of water is decreased and the rpm is also decreased at a certain condition of working. The effect of each of these changes will be to X power delivered due to decrease in head and to \[\gamma \] power delivered due to decrease in rpm?. \[\frac{N\sqrt{Q}}{{{H}^{3/4}}}\] X and Y stand respectively for:

A)

Decrease and increase

B)

Increase and increase

C)

Decrease and decrease

D)

Increase and decrease.

View Solution

37)

Specific speed of a pump and specific speed of a turbine are: (symbols have the usual meaning)

A)

\[\frac{N\sqrt{Q}}{{{H}^{3/4}}}\] and \[\frac{N\sqrt{P}}{{{H}^{5/4}}}\] respectively

B)

\[\frac{N\sqrt{Q}}{{{H}^{3/4}}}\] and \[\frac{N\sqrt{P}}{{{H}^{3/4}}}\] respectively

C)

\[\frac{N\sqrt{Q}}{{{H}^{5/4}}}\] and \[\frac{N\sqrt{P}}{{{H}^{5/4}}}\] respectively

D)

\[\frac{N\sqrt{Q}}{{{H}^{5/4}}}\] and \[\frac{N\sqrt{P}}{{{H}^{3/4}}}\] respectively

View Solution

38)

The following lists refer to fluid machinery Match List-I with List-II and select the correct answer using the codes given below the Lists:

List-I		List-II
A.	Draft tube	1.	Impulse turbine
B.	Surging	2.	Reciprocating pump
C.	Air Vessel	3.	Reaction turbine
D.	Nozzle	4.	Centrifugal pump

Codes:

A)

A\[\to \]4, B\[\to \]3, C\[\to \]2, D\[\to \]1

B)

A\[\to \]3, B\[\to \]4, C\[\to \]2, D\[\to \]1

C)

A\[\to \]3, B\[\to \]4, C\[\to \]1, D\[\to \]2

D)

A\[\to \]4, B\[\to \]3, C\[\to \]1, D\[\to \]2

View Solution

39)

Match List-I with List-II and select the correct answer using the codes given below the lists:

List-I (Tapes of turbines)		List-II (Characteristics of turbines)
A.	Propeller	1.	Inward flow reaction
B.	Francis	2.	Tangential flow impulse
C.	Kaplan	3.	Axial flow reaction with fixed vanes
D.	Pelton	4.	Axial flow reaction with adjustable vanes

Codes:

A)

A\[\to \]2, B\[\to \]4, C\[\to \]1, D\[\to \]3

B)

A\[\to \]3, B\[\to \]4, C\[\to \]1, D\[\to \]2

C)

A\[\to \]2, B\[\to \]1, C\[\to \]4, D\[\to \]3

D)

A\[\to \]3, B\[\to \]1, C\[\to \]4, D\[\to \]2

View Solution

40)

Which of the following are the functions of a volute casing in a centrifugal pump?

1. To collect water from the periphery of the impeller and to transmits it to the delivery pipe at a constant velocity.

2. To increase the discharge of the pump.

3. To increase the efficiency of the pump.

4. To reduce the loss of head in discharge.

Select the correct answer from the codes given below:

A)

1, 2 and 3

B)

2, 3 and 4

C)

1, 3 and 4

D)

1 and 2

View Solution

41)

The movable wicket gates of a reaction turbine are used to:

A)

Control the flow of water passing through the turbine

B)

Control tile pressure under which the turbine is working.

C)

Strengthen the casing of the turbine.

D)

Reduce the size of the turbine.

View Solution

42)

Which of following are the beneficial effects of air vessel fitted to delivery side of a reciprocating pump?

1. Constant rate of discharge can be ensured

2. Power consumption can be reduced

3. Discharge can he increased

4. Constant velocity of the piston can he ensured.

Select the correct answer using the codes given below:

A)

1 and 4

B)

1 and 2

C)

2 and 4

D)

1 and 3

View Solution

43)

For attaining a non-overloading characteristic in centrifugal pumps:

A)

Backward bent vanes are preferred over forward bent vanes.

B)

Forward bent vanes are preferred over backward bent vanes.

C)

Forward bent vanes are preferred over vanes radial at outlet.

D)

Vanes radial at outlet are preferred over backward vanes.

View Solution

44)

Consider the following statements:

Cavitation in hydraulic machines occurs at the

A)

1 and 2 are correct

B)

1 and 3 are correct

C)

1, 2 and 3 are correct

D)

2 and 3 are correct

View Solution

45)

Euler equation for water turbine is derived on the basis of:

A)

conservation of mass

B)

Rate of change of linear momentum

C)

Rate of change of angular momentum

D)

Rate of change of velocity.

View Solution

46)

The Specific speed of a turbine is defined as the speed of a member of the same homologous series of such a size that it:

A)

Delivers unit discharge at unit head.

B)

Delivers unit discharge at unit power.

C)

Delivers unit power at unit discharge.

D)

Produces unit power under the unit head.

View Solution

47)

Match List-I with List-II and select the correct answer.

List-I		List-II
A.	Pelton wheel (single jet)	1.	Medium discharge, low head
B.	Francis Turbine	2.	High discharge, low head
C.	Kaplan Turbine	3.	Medium discharge medium head
		4.	Low discharge high head

Codes:

A)

A\[\to \]1, B\[\to \]2, C\[\to \]3

B)

A\[\to \]1, B\[\to \]3, C\[\to \]4

C)

A\[\to \]4, B\[\to \]1, C\[\to \]3

D)

A\[\to \]4, B\[\to \]3, C\[\to \]2

View Solution

48)

Consider the following statement:

If pump NFSH requirements are not satisfied, then

1. It will not develop sufficient head to raise water.

2. Its efficiency will be low.

3. It will deliver very low discharge.

4. It will be cavitated.

Of these statements:

A)

1, 2 and 3 are correct

B)

1 and 4 are correct

C)

2, 3 and are 4 correct

D)

1, 2, 3 and 4 are correct.

View Solution

49)

In reaction turbines, the draft tube is used:

A)

For the safety of the turbine.

B)

To convert the kinetic energy of flow by a gradual expansion of the flow cross-section.

C)

To destroy the undesirable eddies.

D)

For none of the above purposes.

View Solution

50)

Given that N = speed, P = Power, H = heat The specific speed of a hydraulic turbine is given by:

A)

\[\frac{N\sqrt{P}}{{{H}^{4/5}}}\]

B)

\[\frac{N\sqrt{P}}{{{H}^{5/4}}}\]

C)

\[\frac{P\sqrt{N}}{{{H}^{4/5}}}\]

D)

\[\frac{P\sqrt{N}}{{{H}^{5/4}}}\]

View Solution

51)

As water flows through the runner of a reaction turbine, pressure acting on it would vary from:

A)

More than atmospheric pressure to vacuum

B)

Less than atmospheric pressure to zero gauge pressure

C)

Atmospheric pressure to more than atmospheric pressure

D)

Atatmospheric pressure to vacuum.

View Solution

52)

Consider the following statements regarding torque converter:

1. It has a stationary set of blades in addition to the primary and secondary rotors.

2. It can be used for multiplication of torques.

3. The maximum efficiency of a inverter is less than that of a fluid coupling

4. In a converter designed to give a large increase of torque, the efficiency........speed ratio approaches unity.

Of these statements:

A)

1, 2, 3 and 4 are correct

B)

1, 2 and 3 are correct

C)

1, 2 and 4 are correct

D)

3 and 4 are correct

View Solution

53)

In contrast to fluid couplings, torque Converters are operated:

A)

While completely filled with liquid

B)

While partially filled with liquid

C)

Without liquid

D)

While completely filled with air.

View Solution

54)

Which one of the following statements regarding an impulse turbine is correct?

A)

There is no pressure variation in flow over the buckets and the fluid fills the passageway between the buckets

B)

There is no pressure variation in flow over the buckets and the fluid does not fill the passageway between the buckets

C)

There is pressure drop in flow over the buckets and the fluid fills the passageway between the buckets

D)

There is pressure drop in flow over the buckets and the fluid does not fill the passageway between the buckets.

View Solution

55)

A centrifugal pump is started with its delivery valve kept:

A)

Fully open

B)

fully closed

C)

Partially open

D)

50% open.

View Solution

56)

Which one of the following forms of draft tube will NOT improve the hydraulic efficiency of the turbine?

A)

Straight cylindrical

B)

Conical type

C)

(e) Bell-mouthed

D)

Bent tube.

View Solution

57)

Which one of the following turbines is used in underwater power stations?

A)

Pelton turbine

B)

Deriaz turbine

C)

Tubular turbine

D)

Turgo-impulse turbine.

View Solution

58)

A pelton wheel is ideally suited for:

A)

High head and low discharge

B)

High head and high discharge

C)

Low head and low discharge

D)

Medium head and medium discharge

View Solution

59)

Consider the following turbines:

1. Kaplan

2. Pelton wheel

3. Francis

The correct sequence in increasing order of the specific speeds of these turbines is:

A)

2, 3, 1

B)

2, 1, 3

C)

3, 1, 2

D)

1, 2, 3

View Solution

60)

Consider the following statements regarding the specific speed of a centrifugal pump:

1. Specific speed is defined as the speed of a geometrically similar pump developing unit power under unit head.

2. At the same specific speed, the efficiency is greater with larger capacity

3. The specific speed increases with increase in outer blade angle

4. The specific speed varies directly as the square root of the pump discharge.

Of these statements:

A)

1 and 2 are correct

B)

2 and 4 are correct

C)

3 and 4 are correct

D)

2 and 3 are correct

View Solution

61)

Which of the following purposes are served by the volute casing of a centrifugal pump?

1. Increase in the efficiency of the pump.

2. Conversion of part of the pressure head to velocity head.

3. Giving uniform flow of the fluid coming out of the impeller.

Select the correct answer using the codes given below:

A)

1 and 2

B)

1 and 3

C)

2 and 3

D)

1, 2 and 3

View Solution

62)

Consider the following statements:

1. A draft tube may be fitted to the tail end of a Pelton head.

2. Kaplan turbine is an axial flow reaction turbine with adjustable vanes on the

3. Modem Francis turbine is a mixed flow reaction turbine.

Which of these statements are correct?

A)

1, 2 and 3

B)

1 and 2

C)

2 and 3

D)

1 and 3.

View Solution

63)

Consider the following data for the performance of a centrifugal pump: Speed: 1200 rpm, flow rate 30 \[l/s,\] head 5 k W If the speed is increased to 1500 rpm, the power will be nearly equal to:

A)

6.5 kW

B)

8.7 kW

C)

9.8 kW

D)

10.9 kW

View Solution

64)

Consider the following pumps:

1. Centrifugal pump, single-stage

2. Centrifugal pump, multi-stage

3. Reciprocating pump

4. Jet pump

The pump (s) which can be used to lift water through a suction head of 12 m from a well would include:

A)

2 alone

B)

1, 3 and 4

C)

4 alone

D)

1 and 3

View Solution

65)

If \[{{\omega }_{s}}\] and \[{{\omega }_{p}}\] represent the angular velocities of driven and driving members of a fluid coupling respectively, then the slip is equal to:

A)

\[1-\frac{{{\omega }_{s}}}{{{\omega }_{p}}}\]

B)

\[\frac{{{\omega }_{s}}}{{{\omega }_{p}}}\]

C)

\[\frac{{{\omega }_{p}}}{{{\omega }_{s}}}\]

D)

\[1-\frac{{{\omega }_{p}}}{{{\omega }_{s}}}\]

View Solution

66)

Hydraulic ram is a pump which works on the principle of:

A)

Water hammer

B)

Centrifugal action

C)

Reciprocating action

D)

Hydraulic press

View Solution

67)

The correct sequence of the given hydraulic turbines in decreasing order of their specific speeds is:

A)

Pelton wheel, Francis turbine, Kaplan turbine

B)

Propeller turbine, Francis turbine, Pelton wheel

C)

Kaplan turbine, Pelton wheel, Francis turbine

D)

Francis turbine, Kaplan turbine, Pelton wheel.

View Solution

68)

Which one of the following pairs of formulae represents the specific speeds of turbine and pump respectively? (Notations have their usual meanings),

A)

\[d\frac{N{{Q}^{1/2}}}{{{H}^{3/4}}}\] and \[\frac{N{{P}^{1/2}}}{{{H}^{5/4}}}\]

B)

\[\frac{N{{Q}^{1/2}}}{{{H}^{3/4}}}\] and \[\frac{N{{P}^{1/2}}}{{{H}^{3/4}}}\]

C)

\[\frac{N{{P}^{1/2}}}{{{H}^{5/4}}}\] and \[\frac{N{{Q}^{1/2}}}{{{H}^{5/4}}}\]

D)

\[\frac{N{{P}^{1/2}}}{{{H}^{3/4}}}\] and \[\frac{N{{Q}^{1/2}}}{{{H}^{5/4}}}\]

View Solution

69)

Consider the following turbines/wheels:

1. Francis turbine

2. Pelton wheel with two or more jets

3. Pelton wheel with a single jet

4. Kaplan turbine.

The correct sequence of these turbines/wheels in increasing order of their specific speeds is:

A)

2, 3, 1, 4

B)

3, 2, 1, 4

C)

2, 3, 4, 1

D)

3, 2, 4, 1

View Solution

70)

The gross head available to a hydraulic power plant is 100 m. The utilized head in the runner of the hydraulic turbine is 72 m. If the hydraulic efficiency of the turbine is 90%, the pipe friction head is estimated to be:

A)

20 m

B)

18 m

C)

16.2 m

D)

1.8 m

View Solution

71)

Air cooling is used for Freon compressors whereas water jacketing is adopted for cooling ammonia compressors. This is because

A)

Latent heat of ammonia is higher than that of freon

B)

Thermal conductivity of water is higher than that of air

C)

Specific heat of water is higher than that of air

D)

Of the larger superheat from of ammonia compression cycle.

View Solution

72)

Consider the following statements regarding the volute casing of a centrifugal pump:

1. Loss of head due to change in velocity is eliminated.

2. Efficiency of the pump is increased.

3. Water from the periphery of the impeller is collected and transmitted to the delivery pipe at constant velocity.

Which of these statements are correct?

A)

1, 2 and 3

B)

1 and 2

C)

2 and 3

D)

1 and 3

View Solution

73)

The cavitation number of any fluid machineryis defined as \[\sigma =\frac{p-p'}{p{{v}^{2}}/2}\] (p is absolute pressure, \[\rho \]is density and v is free stream velocity) The symbol p? denotes:

A)

Static pressure of fluid

B)

Dynamic pressure of fluid

C)

vapour pressure of fluid

D)

Shear stress of fluid.

View Solution

74)

Consider the following statements:

A water turbine governor

1. Helps in starting and shutting down the turbo unit.

2. Controls the speed of turbine set to match it with the hydroelectric system.

3. Sets the amount of load which a turbine unit has to carry

Which of these statements are correct?

A)

1, 2 and 3

B)

1 and 2

C)

2 and 3

D)

1 and 3

View Solution

75)

Consider the following statements regarding a torque converter: '

1. Its maximum efficiency is less than that of the fluid coupling

2. It has two runners and a set of stationary vanes interposed between them.

3. It has two runners.

4. The ratio of secondary to primary torque is zero for the zero value of angular velocity of secondary.

Which of these statements are correct?

A)

1 and 2

B)

3 and 4

C)

1 and 4

D)

2 and 4

View Solution

76)

Consider the specific speed ranges of the following types of turbines:

1, Francis

2. Kaplan

3. Pelton

The sequence of their Specific speed in increasing order is:

A)

1, 2, 3

B)

3, 1, 2

C)

3, 2, 1

D)

2, 3, 1.

View Solution

77)

In a PERT network, expected project duration in found to be 36 days from the start of the project. The variance is four days. The probability that the project will be completed in 36 days is?

A)

Zero

B)

34%

C)

50%

D)

84%

View Solution

78)

The variance \[\left( {{V}_{1}} \right)\] for critical path \[a\to b=4\] time units, \[b\to c=16\] units, \[c\to d=4\] time units, \[d\to e=1\] time unit. The standard deviation of the critical path \[a\to e\] is:

A)

3

B)

4

C)

5

D)

6

View Solution

79)

Estimated time T, and variance of the activities 'V on the critical path in a PERT new work are given in the following table:

Activity	\[{{\mathbf{T}}_{\mathbf{e}}}\] (days)	V \[{{\left( \mathbf{days} \right)}^{\mathbf{2}}}\]
a	17	4
b	15	4
c	8	1

The probability of completing the project in 43 days is:

A)

15.6%

B)

50.0%

C)

81.4%

D)

90.0%

View Solution

80)

The earliest occurrence time for event 'I' is 8 weeks and the latest occurrence time for events 'I' is 26 weeks. The earliest occurrence time for evens '2' is 32 weeks and the latest occurrence time for events '2' is 37 weeks. If the activity time is 11 weeks, then the total float will be:

A)

11

B)

13

C)

18

D)

27

View Solution

81)

Consider the following statements:

Thermal stress is induced in a component in general, when

1. A temperature gradient exists in the component.

2. The component is free from any restraint.

3. It is restrained to expand or contract freely.

Which of the above statements is/are correct?

A)

1 and 2

B)

2 and 3

C)

3 alone

D)

2 alone.

View Solution

82)

Consider the following statements in case of beams:

1. Rate of change of shear force is equal to the rate of loading at a particular section.

2. Rate of change of bending moment is equal to the shear force at a particular section.

3. Maximum shear force in a beam occurs at a point where bending moment is either zero or bending moment changes sign.

Which of the above statement is/are correct'?

A)

1 alone

B)

2 alone

C)

1 and 2

D)

1, 2 and 3.

View Solution

83)

Which of the following are fabricated using engineering plastics?

1. Surface plate

2. Gears

3. Guide ways for machine tools

4. Foundary patterns.

Select the correct answer using the codes given below: Codes:

A)

1, 2 and 3

B)

1

C)

2, 3 and 4

D)

1, 2, 3 and 4.

View Solution

84)

Consider the following statements: Polytetrafluoro-ethane is

1. A thermoplastic material.

2. Having high friction co-efficient.

3. A thermosetting material.

4. Having low friction co-efficient.

5. An electric insulator.

6. non-sticking to surfaces.

Which of the above statements are correct?

A)

1, 2 and 5

B)

2, 3 and 6

C)

3, 4 and 5

D)

3, 2 and 5.

View Solution

85)

Which of the following fibre materials are used for reinforcement in composite materials:

1. Glass

2. Boron carbide

3. Graphite

Select the correct answer using the codes given below: Codes:

A)

1 and 2

B)

1 and 3

C)

2 and 3

D)

1, 2 and 3.

View Solution

86)

Consider the following statements:

The strength of a single point cutting tool depends upon

1. Rake angle

2. Clearance angle

3. Lip angle.

Which of these statements are correct?

A)

1 and 3

B)

2 and 3

C)

1 and 2

D)

1, 2 and 3.

View Solution

87)

Which of the following materials are used in Grinding wheel?

1. Aluminum oxide

2. Cubic boron nitride

3. Silicon carbide.

Select the correct answer using the codes given below:

Codes:

A)

1, 2 and 3

B)

1 and 2

C)

2 and 3

D)

1 and 3.

View Solution

88)

Consider the following statements related piereing and blanking:

1. Shear on the punch reduces the maximum cutting force.

2. Shear increases the capacity of the press needed.

3. Shear increases the life of the punch.

4. The total energy needed to make the cut remains unaltered due to provision of shear.

Which of the above statements are correct?

A)

1 and 2

B)

1 and 4

C)

2 and 3

D)

3 and 4.

View Solution

89)

Consider the following steps involved in hammer forging a connecting rod from bar stock:

Which of the following is the correct sequence of operations?

A)

1, 4, 3, 2 and 5

B)

4, 5, 1, 3 and 2

C)

5, 4, 3, 2 and 1

D)

5, 1, 4, 2 and 3

View Solution

90)

The graph shows the results of various quality levels for a component

Consider the following statements:

1. Curve A shows the variation of value of component.

2. Curve B shows the variation of cost of the component.

3. Graph is called as fish bone diagram.

4. The preferred level of quality is given by line CC.

5. The preferred level of quality is given by line DD.

Which of the above statements are correct?

A)

1, 2 and 5

B)

1, 3 and 4

C)

2, 3 and 4

D)

1, 2 and 4

View Solution

Railways NTPC (Technical Ability) Instrument Mechanical Question Bank

done Instrument Mechanical Total Questions - 90

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Questions - Instrument Mechanical

Instrument Mechanical Total Questions - 90