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Latest JSSC JE Mechanical Exam Question (Objective Questions), MCQ in English

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Question Bank JSSC JE Mechanical (Paper-II) - English

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Mechanical

Question 1Single Answer

A fin will be more effective when Bio number is

A
Greater than 1
B
Equal to 1
C
Between 1 and 3
4 4
D
Less than 1

Question 2Single Answer

A tank of length, breadth and height in the ratio of 2:1:2 is full of water. The ratio of hydrostatic force at the bottom to that at any larger vertical surface is

Question 3Single Answer

Which of the following fluids exhibit a certain shear stress at zero shear strain rate followed by a straight line relationship between shear stress and shear strain rate?

A
Newtonian fluid
B
Ideal Bingham plastic fluids
C
Pseudo-plastic fluids
D
Dilatent fluids

Question 4Single Answer

What is the specific gravity of a marble stone, which weighs 400N in air, and 200N in water? (g=10m/s²)

Question 5Single Answer

What is the intensity of pressure in the following SI units, when specific gravity of mercury is 13.6 and the intensity of pressure is 400KPa ?

A
0.3 bar or 4.077m of water or 0.29 mm of Hg
B
4 bar or 5.077m of water or 0.399 mm of Hg
C
0.3 bar or 5.077m of water or 0.599 mm of Hg
D
4 bar or 4.077m of water or 0.299 mm of Hg

Question 6Single Answer

Consider the following statements:
1.If a small upward displacement is given to a floating body, it results in the reduction of the buoyant force acting on the body
2.A slight horizontal displacement does not change either the magnitude or the location of the buoyant force
Which of the above statements is/are correct?

A
Both 1 and 2
B
1 only
C
2 only
D
Neither 1 nor 2

Question 7Single Answer

State whether following flow field is physically possible?

A
Possible for steady, incompressible flow
B
Possible for unsteady, incompressible flow
C
Possible for steady, compressible flow
D
Not Possible

Question 8Single Answer

In a differential manometer, a head of 0.5 m of fluid A in limb 1 is found to balance a head of 0.3 m of fluid B in limb 2. The atmospheric pressure is 760 mm of mercury. The ratio of specific gravities of A to B is

A
0.25
B
0.26
C
2
D
4

Question 9Single Answer

A Reversed Carnot Engine removes 50 kW from a heat sink. The temperature of the heat sink is 250 K and the temperature of the heat reservoir is 300 K. The power required of the engine is

A
10 kW
B
20 kW
C
30 kW
D
50 kW

Question 10Single Answer

On which of the following just in time manufacturing philosophy emphasizes ?

A
man power
B
profit
C
inventory
D
manufacturing

Question 11Single Answer

In a stream line steady flow, two points A and B on a stream line are 1m apart and the flow velocity varies uniformly from 2m/s to 5m/s. What is the acceleration of fluid at B?

A
3 m/s²
B
6 m/s²
C
9 m/s²
D
15 m/s²

Question 12Single Answer

The stream function is given by Ψ = 3xy, then the velocity at the point (2,3) is

A
9
B
-6
C
117
D
10.8

Question 13Single Answer

The boundary layer thickness at a given distance from the leading edge of a flat plate is

A
More for lighter fluid
B
More for denser fluid
C
Less for denser fluid
D
Less for lighter fluid

Question 14Single Answer

In a laminar flow through a circular pipe, the discharge varies

A
Linearly with fluid density
B
Inversely with pressure drop
C
Directly as square of pipe radius
D
Inversely with fluid velocity

Question 15Single Answer

A fluid is flowing over a flat plate. At distance of 8 cm from the leading edge, the Reynolds number is found to be 25600. The thickness of the boundary layer at this point is

A
1.5mm
B
2.5mm
C
4.0mm
D
5.0mm

Question 16Single Answer

Air is flowing over a flat plate with a free stream velocity of 24 m/s, and its kinematic viscosity is 72 ×10^-6m²/s. If at a particular point, the Reynolds number is 30000, its location from the leading edge is

A
0.05m
B
0.07m
C
0.08m
D
0.09m

Question 17Single Answer

In a refrigerator, the evaporator and condenser coil temperatures are –33°C and 27°C, respectively. Assuming that the maximum COP is realized, the required power input for a refrigerating effect of 4 kW is

A
8 kW
B
4 kW
C
2 kW
D
1 kW

Question 18Single Answer

In a hydraulic coupling

A
The magnitudes of input and output torques are equal
B
The magnitudes of input torque is greater than output torque
C
The magnitudes of input torque is less than output torque
D
The magnitudes of input torque is negligible as compared to output torque

Question 19Single Answer

Consider the following statements:
1.The wheel can be operated freely in air
2.Pressure at the exit of the nozzle is atmospheric
3.Pressure does not vary along the moving vanes
4.Change the direction of momentum imparts thrust over moving vanes Which of the following statements are applied to impulse turbine?

A
1,2 and 3 only
B
1,2 and 4 only
C
3 and 4 only
D
1,2, 3 and 4

Question 20Single Answer

A water jet 0.0015m²in area issues from a nozzle with 15 m/s velocity. It is made to impinge perpendicular on to a plate that moves away from the jet with a velocity of 5 m/s. The force on the plate due to this impact is

A
150 N
B
1470 N
C
340 N
D
900 N

Question 21Single Answer

Consider the following statements with regard to hydraulic turbines:
1.Kaplan turbines are most efficient at part load operations.
2.If n is the number of jets in a Pelton turbine, then the specific speed is proportional to n².
3.The flow ratio of Francis turbines are in the range of 0.1 – 0.3.
Which of the above statements is/are correct?

A
1,2 and 3
B
1 and 2 only
C
1 and 3 only
D
2 and 3 only

Question 22Single Answer

Which of the following is a Vector quantity ?

A
Energy
B
Mass
C
Momentum
D
Angle

Question 23Single Answer

Bernoulli’s equation is applicable between any two points located in

A
Rotational flow of an incompressible fluid
B
Irrotational flow of compressible or incompressible fluid
C
Steady, rotational flow of an incompressible fluid
D
Steady, irrotational flow of an incompressible fluid

Question 24Single Answer

Water flows through a smooth circular pipe of diameter D and length L because of a pressure difference ΔP across the length. The volume flow rate is Q and the flow is turbulent with Reynolds number 10⁵. If the pressure difference is increased to 4ΔP the volume flow rate will be

A
2Q
B
A little more than 2Q
C
A little less than 2Q
D
4Q

Question 25Single Answer

Heat is lost from a 100 mm diameter steam pipe placed horizontally in ambient air at 30°C. If the Nusselt number is 25 and the thermal conductivity of the air is 0.03 W/m K, then the heat transfer coefficient will be

A
7.5 W/m²K
B
15 W/m²K
C
25 W/m²K
D
35 W/m²K

Question 26Single Answer

For laminar flow through a round pipe, the shear stress

A
Remains constant over the cross-section
B
Varies linearly with the radial distance
C
Must be zero at all point
D
Varies parabolically with radial distance

Question 27Single Answer

Percentage clongation during tensile test is indicative of

A
Creep
B
Malleability
C
Ductility
D
Elasticity in the metal

Question 28Single Answer

Which of the above statements is not correct in the context of laminar flow through a pipeline?

A
Shear stress is zero at the center and varies linearly with pipe radius
B
Head loss is proportional to square of the average flow velocity
C
The friction factor varies inversely with flow Reynolds number
D
No dispersion of die injected into the flow stream

Question 29Single Answer

Laminar flow between closely spaced parallel plates is governed by the consideration of which one of the following pair of forces?

A
Pressure and inertial forces
B
Gravity and inertial forces
C
Viscous and inertial forces
D
Pressure and inertial forces

Question 30Single Answer

Formation and collapse of vapour bubbles are believed to be the root cause for cavitation in hydraulic turbines. Most favorable condition for the formation of bubbles is set in the turbine at

A
Penstock/nozzl
B
Guide vanes/Inlet of the runner
C
Vanes receiving impact of jet
D
Outlet of the runner/Entrance of the draft tube

Question 31Single Answer

For fully developed laminar flow through a circular pipe with Reynolds number Rethe friction factor is

A
Inversely proportional to Re
B
Proportional to Re
C
Proportional to square of Re
D
Independent of Re

Question 32Single Answer

The ratio of power outlet of the pump to the power input to the pump is known as

A
Mechanical efficiency
B
Static efficiency
C
Overall efficiency
D
Manometric efficiency

Question 33Single Answer

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

Question 34Single Answer

The specific speed of a pump is defined as the speed of the unit of such a size that is

A
Delivers the unit discharge at unit head
B
Requires unit power to develop unit head
C
Delivers the unit discharge at unit power
D
Produces unit power with unit head available

Question 35Single Answer

Negative slip occurs in reciprocating pumps, when delivery pipe is

A
Long and suction pipe is short and pump is running atlow speed
B
Long and suction pipe is short and pump is running at high speed
C
Short and suction pipe is long and pump is running at low speed
D
Short and suction pipe is long and pump is running at high speed

Question 36Single Answer

The pressure inside a soap bubble of 50 mm diameter is 25 N/m² above the atmospheric pressure. The surface tension in soap film would be

A
0.156 N/m
B
0.313 N/m
C
0.624 N/m
D
0.078 N/m

Question 37Single Answer

A Newtonian fluid is one which

A
Is viscous but incompressible
B
Has a linear relationship between the shear stress and the rate of angular deflection
C
Exhibits an increase in viscosity with increasing rate of deformation
D
Exhibits a decrease in viscosity with increasing rate of deformation

Question 38Single Answer

Unlike the viscosity of fluids, the viscosity of gases increases with increasing temperature. This is due to

A
Increased cohesive force between the molecule
B
Increased momentum transfer in the molecules
C
Decreased momentum transfer in the molecules
D
Increase in both cohesive force and momentum transfer

Question 39Single Answer

Manometer is a device used for measuring

A
Velocity at a point in a fluid
B
Pressure at a point in a fluid
C
Discharge of a fluid
D
None of the above

Question 40Single Answer

When a dolphin glides through air, it experiences an external pressure of 0.75 m of mercury. The absolute pressure on dolphin when it is 5m below the free surface of the water is

A
0.10 N/m²
B
0.5 N/m²
C
1.0 N/m²
D
0.15 N/m²

Question 41Single Answer

Which of the above statements is correct?

A
For a floating body, the stable equilibrium condition exists when position of metacenter remains higher than the center of gravity of the body
B
For a floating body, the stable equilibrium condition exists when position of metacenter remains lower than the center of gravity of the body
C
For a floating body, the neutral equilibrium condition exists when position of metacenter remains higher than the center of gravity of the body
D
For a floating body, the unstable equilibrium condition exists when position of metacenter remains higher than the center of gravity of the body

Question 42Single Answer

A wall of 0.6m thickness has normal area of 1.5 m² and is made up of material of thermal conductivity 0.4 W/mK. If the temperature on the two sides of the wall are 800°C and 1000°C, the thermal resistance of the wall is

A
1.8 K/W
B
1.8 W/K
C
1 K/W
D
1 W/K

Question 43Single Answer

A flownet is a graphical representation of streamlines and euqipotnetial lines such as these lines

A
Intersect each other at various different angles forming irregular shaped nets
B
Intersect each other orthogonally forming curvilinearsquares
C
Indicate the direction but not magnitude of vector
D
Indicate the direction and magnitude of vector

Question 44Single Answer

Which of the above statements is correct for the velocity of potential?

A
Existence of velocity potential is an indication of irrotational nature of the flow
B
The velocity potential automatically satisfies the continuity equation
C
Velocity potential can be defined only for 2-dimensional flow
D
All of the above

Question 45Single Answer

Angle of diverging portion of the venturimeter is limited to 7°, because:
1.Flow decelerates in the diverging portion and pressure increases in the downstream direction. Hence, the fluid experience an adverse pressure gradient, if the divergence angle is large.
2 .Flow separation takes place due to adverse pressure gradient when divergence angle is large.
3 .If the divergence angle is large, a negative pressure is created at the throat which obstructs the flow of fluid.
Which of the above reasons are correct?

A
1, 2 and 3
B
1 and 2 only
C
1 and 3 only
D
2 and 3 only

Question 46Single Answer

A gas is flowing through an insulated nozzle. If the inlet velocity of gas is negligible and there is an enthalpy drop of 45kJ/kg, the velocity of gas leaving the nozzle is

A
100m/s
B
200m/s
C
300m/s
D
350m/s

Question 47Single Answer

Which of the above statements are correct for turbo-prop powered aircrafts?
1 .The propulsion efficiency of turbo-prop is higher than that of turbo-jet and rockets for low speeds up to about 800km/hr.
2.For the same thrust the turbine in the turbo prop aircraft is smaller than in the turbo-jet aircraft.
3.For the turbo-prop the flight velocity cannot exceed the jet velocity.

A
1,2 and 3
B
1 and 2 only
C
2 and 3 only
D
1 and 3 only

Question 48Single Answer

If absolute jet exit velocity from a jet engine is 2800m/s and forward flight velocity is 1400m/s then propulsive efficiency is

A
33.33%
B
40%
C
66.66%
D
90%

Question 49Single Answer

An air-breathing aircraft is flying at an altitude where the air density is half the value at ground level. With reference to the ground level, the air fuel ratio at this altitude will be

A
1
2
B
1
C
2
D
4

Question 50Single Answer

Which of the above statements are correct for rockets?
1.Unlike the turbo-jet aircraft, in rockets the flight velocity can exceed the jet velocity.
2.In rockets gases having lower molecular weight increase the specific thrust.
3.In rockets the gases are expanded in the nozzle up to the atmospheric pressure.

A
1,2 and 3
B
1 and 2 only
C
2 and 3 only
D
1 and 3 only

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Mechanical

Question 51Single Answer

In a differential manometer a head of 0.6m of fluid A in limb 1 is found to balance a head of 0.3m of fluid B in limb 2. The ratio of specific gravities of A to B is

A
2
B
0.5
C
0.3
D
0.18

Question 52Single Answer

At x = 0, the function f (x) = |x| will be

A
minimum
B
maximum
C
point of inflection
D
neither minimum nor maximum

Question 53Single Answer

The center of pressure of a plane submerged surface

A
Is a point on the submerged area at which the resultant hydrostatic force is supposed to act
B
Should always coincide within the center of submerged area
C
Should be at the center of gravity of the plane surface
D
Is always below the centroid of area

Question 54Single Answer

A furnace is provided with an insulating refractory lining. The overall thermal conductivity of the material is 0.03 W/mK. The thickness of the lining is 100 mm. The inner and outer temperatures are 250°C and 50°C, respectively. The heat loss to the surroundings will be

A
30 J/m²/s
B
60 J/m²/s
C
60 J/s
D
30 J/s

Question 55Single Answer

A piece of metal of specific gravity 7 floats in mercury of specific gravity 13.6, what fraction of its volume is under mercury?

A
0.5
B
0.4
C
0.515
D
Fully immersed

Question 56Single Answer

A right circular cylinder, open at the top, is filled with a liquid of specific gravity 1.2, and rotated about its vertical axis at such a speed that half of the liquid spills out. The pressure at the center of the bottom is

A
Zero
B
One-fourth its value when the cylinder was full
C
One-third its value when the cylinder was full
D
three-fourth its value when the cylinder was full

Question 57Single Answer

Consider the following statements about velocity potential:
1.Velocity potential is a vector function similar to stream function
2.It is a fully three dimensional function and not limited to two
coordinates
3.Velocity potential does not exist at stagnation points
4.Velocity potential exists only if the flow is irrotational
Which of the above statements are correct?

A
1, 2 and 3
B
1, 2 and 4
C
1, 3 and 4
D
2, 3 and 4

Question 58Single Answer

During a constant pressure expansion of a gas, 33.3% heat is converted into work while the temperature rises by 20 K. The specific heat of the gas at constant pressure as a proportion of work, W is

A
8%
B
10%
C
12%
D
15%

Question 59Single Answer

Principle mechanism of material removal in ECM?

A
Chemical corrosion
B
Ionic dissolution
C
Both (a) and (b)
D
Non of the above

Question 60Single Answer

The centre-line velocity in a pipe flow is 2m/s. What is the average flow velocity in the pipe if the Reynolds number of the flow is 800?

A
2 m/s
B
1.5 m/s
C
1 m/s
D
0.5 m/s

Question 61Single Answer

In flow through a pipe, the transition from laminar to turbulent flow does not depend on

A
Density of fluid
B
Length of pipe
C
Diameter of pipe
D
Velocity of the fluid

Question 62Single Answer

A 0.20m diameter pipe 20m long transports oil at a flow rate of0.01m³/s. Calculate power required to maintain flow if dynamic viscosity and density of oil is 0.08 Pas and 900 kg/m³ respectively

A
4.064 kW
B
3.074 kW
C
5.064 kW
D
4.074 kW

Question 63Single Answer

Pressure loss for laminar flow through pipeline is dependent

A
Inversely on flow of velocity
B
Directly on square of pipe radius
C
Directly on length of pipe
D
Inversely on viscosity of flowing medium

Question 64Single Answer

Fanno line is a flow in a constant area duct

A
With friction and heat transfer but in the absence of work
B
With friction and heat transfer accompanied by work
C
With friction but in the absence of heat transfer or work
D
Without friction but accompanied by heat transfer and work

Question 65Single Answer

In an adiabatic flow with friction through a constant area duct, the following phenomenon are predicted:
1.The flow downstream tends to be sonic irrespective of the Mach-number upstream
2.In the case of initially supersonic flow, any increase in duct length beyond choked flow would make the exit flow subsonic
3.In the case of initially subsonic flow, any increase in duct length will not change sonic flow at the exit
4.The optimum pipe length for sonic outlet in supersonic flow is considerably longer than that of subsonic flow for the same flow rate
Which of these are correct?

A
1,2,3 and 4
B
1,2 and 3 only
C
1,3 and 4 only
D
2,3 and 4 only

Question 66Single Answer

In a reciprocating pump, air vessels are used to

A
Smoothen the flow
B
Reduce suction head
C
Increase delivery head
D
Reduce acceleration head

Question 67Single Answer

Consider the following statements pertaining to centrifugal pumps:
1.The inlet to the impeller of a centrifugal pump is always axial, while the outlet may be radial or inclined.
2.The impeller may be shrouded on both sides with an eye at the centre and vanes curved backwards.
3.Impeller of double entry type has a balanced radial thrust.
4.Un-shrouded and part shrouded impeller are used only where high efficiency is unimportant.
Which of these statements are correct?

A
1,2,3 and 4
B
1,2 and 3 only
C
1,2 and 4 only
D
2,3 and 4 only

Question 68Single Answer

A centrifugal pump is fully primed, but on starting it fails to deliver fluid. Thr probable reasons are listed below:
1.Leaky foot valve or suction line
2.Suction head is very slow
3.Insufficient motor speed
4.Damaged or closed delivery valve
Which of these reasons are correct?

A
1,2,3 and 4
B
1,2 and 3 only
C
2,3 and 4 only
D
1,3 and 4 only

Question 69Single Answer

A centrifugal pump is to discharge 0.118 m³/s at speed of 1450 rpm against a head of 25m. The impeller diameter is 25cm, its width at outlet is 5cm and manometric efficiency is 75%. The vane angle at outer periphery of impeller is

A
56.77°C
B
59.77°C
C
61.77°C
D
48.77°C

Question 70Single Answer

A turbine is working under a head of 200m. The power developed by the turbine is 100kW and discharge through the turbine is 0.125 m³/s. In such case, the ratio of unit power to unit discharge for the turbine will be

A
4000
B
16000
C
160 × 10³
D
None of the above

Question 71Single Answer

Two geometrical similar pumps are running at 1000 rpm speed (both). If one pump has impeller diameter of 0.3m and discharges 20Ips against 20m head, and the other pump gives half of this discharge rate; calculate head and diameter of second pump

A
12.5m and 0.12m
B
10.5m and 0.12m
C
10.5m and 0.23m
D
12.5m and 0.23m

Question 72Single Answer

In a steady laminar flow of a given discharge through a circular pipe of diameter D, the head loss is proportional to

A
D^–1
B
D^–2
C
D^–3
D
D^–4

Question 73Single Answer

Frictional losses in the nozzle

A
Reduces the enthalpy of the fluid
B
increases the enthalpy of the fluid
C
no effect on the enthalpy of the fluid
D
None of the above

Question 74Single Answer

In a nozzle designed for maximum discharge conditions, the flow velocity in the convergent section of the nozzle is

A
Subsonic
B
Sonic
C
Supersonic
D
Depends on initial pressure and condition of the steam

Question 75Single Answer

In the centrifugal compressor, the work input is equal to the sum of

A
Pressure head, relative head and dynamic head
B
dynamic head, centrifugal head and relative head
C
Pressure head, centrifugal head and dynamic head
D
Pressure head, centrifugal head and relative head

Question 76Single Answer

For a centrifugal compressor with radial vanes, slip factor is the ratio of

A
Isentropic work to Euler work
B
Whirl velocity to the blade velocity at the impeller exit
C
Stagnation pressure to static pressure
D
Isentropic temperature rise to actual temperature rise

Question 77Single Answer

The specific speed of a centrifugal compressor is generally

A
Less than that of reciprocating compressor
B
Independent of compressor type, but depends only on size of compressor
C
Higher than that of axial compressor
D
More than specific speed of reciprocating compressor but less than axial compressor

Question 78Single Answer

In a centrifugal compressor, the highest Mach number leading to shock wave in the fluid flow occurs at

A
Diffuser inlet radius
B
Diffuser outlet radius
C
impeller inlet radius
D
impeller outlet radius

Question 79Single Answer

The rating of the fuse wire is always expressed in

A
Ampere-hours
B
Ampere-volts
C
KWH
D
Ampere

Question 80Single Answer

In an axial flow compressor, the ratio of pressure rise in the rotor blades to the pressure rise in the compressor in one stage is known as

A
Pressure coefficient
B
Work factor
C
Degree of reaction
D
Slip factor

Question 81Single Answer

CNC machine interpolator controls

A
spindle speed
B
feed to tool
C
motion of tools
D
None of these

Question 82Single Answer

If a row interchanged in the matrix, then the determinant of matrix is

A
magnitude remains same, sign changes
B
magnitude changes, sign remains same
C
both magnitude and sign changes
D
both magnitude and sign remains same

Question 83Single Answer

Water is coming out from a tap and falls vertically downwards. At the tap opening, the stream diameter is 20 mm with uniform velocity of 2 m/s. Assuming steady inviscid flow, constant pressure atmosphere everywhere, and neglecting curvature and surface tension effects, the diameter of the stream 0.5 m below the tap opening is nearly

A
11.7 mm
B
14.6 mm
C
17.5 mm
D
20.4 mm

Question 84Single Answer

A body of mass 20kg falls freely in vacuum. It has fallen through a vertical distance of 50m. The gravitational acceleration may be assumed as 10m/s². What is the thermodynamic work done by the body?

A
1000Nm
B
10kJ
C
zero
D
1kNm

Question 85Single Answer

A closed gaseous system undergoes a reversible constant pressure process at 2bar in which 100 kJ of heat is rejected and the volume changes from 0.2m³ to 0.1m³. The change in the internal energy of the system is

A
- 100kJ
B
-80kJ
C
-60kJ
D
-40kJ

Question 86Single Answer

A Carnot engines receives 100kJ of heat at 600K. Heat is rejected at 300K. The displacement volume is 0.2 m³. The mean effective pressure is

A
2 bar
B
2.5 bar
C
3 bar
D
3.5 bar

Question 87Single Answer

The ratio of static enthalpy rise in the rotor to the static enthalpy rise in the stage of an axial flow compressor is defined as:

A
Power input factor
B
Flow coefficient
C
Temperature coefficient
D
Degree of reaction

Question 88Single Answer

The eigen values of a symmetric matrix are all

A
complex with non-zero position imaginary part
B
complex with non-zero negative imaginary part
C
real
D
pure imaginary

Question 89Single Answer

During a thermodynamic process, 100kJ of heat is transferred from a reservoir at 800K to a sink at 400K. The ambient temperature is 300K. the loss of available energy is

A
27.5 kJ
B
32.5 kJ
C
37.5 kJ
D
62.5 kJ

Question 90Single Answer

The vapor pressure of a liquid at any arbitrary temperature can be estimated approximately with the help of

A
Gibbs equation
B
Joule-Kelvin equation
C
Clausius-Clapeyron equation
D
Gibbs-Duhem equation

Question 91Single Answer

In order to determine the quality of wet steam by a separating and throttling calorimeter, the steam should be first separated and then throttled such that the final state is

A
Saturated vapor only
B
Superheated vapor only
C
At a pressure higher than the original pressure
D
A mixture of saturated liquid and vapor

Question 92Single Answer

A rotor weighing 2 kN is supported on bearings A and B which are 1 m apart. The centre of mass of the rotor is at a distance 0.4 m from bearing A. It is observed that there is an unbalanced couple of magnitude 300 N-m which *leaves the shaft balanced statically. The dynamic reactions at the supports will be

A
800 N and 800 N
B
300 N and 800 N
C
800 N and –300 N
D
300 N and –300 N

Question 93Single Answer

A cam is a mechanical member used to impart a desired motion to a follower by direct contact. Which one of the under-listed follower motion types will produce the least jerk to the system?

A
Simple harmonic
B
Constant acceleration and deceleration
C
Constant velocity
D
Cycloidal

Question 94Single Answer

The tendency of detonation is high in engines of larger cylinder diameter because of

A
Higher intake pressure in larger cylinder
B
Higher fuel/air ration in larger cylinder
C
Flame having to travel longer distance in larger cylinder
D
Sparks are advanced more in larger cylinder

Question 95Single Answer

An open cycle pressure gas turbine uses a fuel of calorific value 40,000 kJ/kg with airfuel ratio of 80 : 1 and develops a net output of 80kJ/kg of air. The thermal efficiency of the cycle is

A
12%
B
16%
C
20%
D
18%
E
25 %

Question 96Single Answer

Consider the following statements regarding cycles:
1.Stirling cycle consists of two isothermal and two adiabatic processes.
2.In vapor compression cycle, the refrigerant is in form of dry saturated vapor before entering compressor.
3.Diesel cycle consists of one constant pressure; one constant volume and two isentropic processes
Which of the above statements are correct?

A
1, 2 and 3
B
1 and 2 only
C
1 and 3 only
D
2 and 3 only

Question 97Single Answer

The efficiency of vapor power Rankine cycle can be increased by
1 .Increasing the temperature of the working fluid at which heat is added
2.Increasing the pressure of the working fluid at which heat is added
3.Decreasing the temperature of the working fluid at which heat is rejected
Which of the above statements are correct?

A
1 and 2 only
B
1 and 3 only
C
2 and 3 only
D
1, 2 and 3

Question 98Single Answer

The velocity of a gas flowing through a duct is 300 m/s; its temperature is 127°C; Gas constant R = 0.25 kJ/kg K, the ratio of specific heat is C_p/C_V = 𝛾 = 1.6. What is the value of Mach number?

A
0.70
B
0.72
C
0.75
D
0.77

Question 99Single Answer

When a system is taken from state ‘x’ to state ‘y’, 30kJ of heat flows into the system and the system does 10kJ of work. When the system is returned from ‘y’ to ‘x’ along another path, work done on the system is 8kJ. What is the amount of heat liberated or absorbed?

A
12 kJ of heat liberated
B
28 kJ of heat liberated
C
12 kJ of heat absorbed
D
28 kJ of heat absorbed

Question 100Single Answer

The values of heat transfer and work transfer for the processes of a thermodynamic cycle are given below:
Process Heat transfer Worktransfer
(kJ) (kJ)
1 300 300
2 0 250
3 -100 -100
4 0 -250
The thermal efficiency of the cycle and the work ratio will be respectively

A
33% and 0.66
B
66% and 0.36
C
36% and 0.66
D
33% and 0.36

Question 101Single Answer

Consider the following statements:
1.The only practical way of improving efficiency of Otto cycle is to increase the compression ratio of an internal combustion engine.
2.Ericsson cycle needs heat transfer in all the processes.
3.Ericsson and Stirling cycles employ regenerative heat exchangers for reversible heat transfer.
4.Atkinson cycle has a greater specific work than a comparable Otto cycle engine.
Which of the above statements are correct?

A
1,2,3 and 4
B
1, 2 and 4 only
C
2, 3 and 4 only
D
1, 2 and 3 only

Question 102Single Answer

For a multistage reciprocating compressor, which of the following statements are correct?
1.It decreases volumetric efficiency
2.The work of compression is reduced
3.The high pressure cylinder is smaller in size

A
1 and 2 only
B
2 and 3 only
C
1 and 3 only
D
1, 2 and 3

Question 103Single Answer

Consider the following statements
1.Free expansion of a gas
2.Slow heating of oil from a constant temperature source
3.Evaporation of water at its saturation temperature by a source at the same temperature
4.Isentropic compression of an ideal gas
Which of these processes are irreversible?

A
1 and 2
B
2 and 3
C
3 and 4
D
1 and 4

Question 104Single Answer

There is a uniform distributed source of heat present in a plane wall whose one side ( x=0) is insulated and other side (x=L) is exposed to ambient temperature (T_∞), with heat transfer coefficient (h). Assuming constant thermal conductivity (k), steady state and one dimensional conduction, the temperature of the wall is maximum at x equal to

A
0
B
L
C
L
2
D
L
4

Question 105Single Answer

An insulating material with a thermal conductivity, k=0.12 W/mK is used for a pipe carrying steam. The local coefficient of heat transfer (h) to the surroudings is 4 W/m²K. In order to provide effective insulation, the minimum outer diameter of the pipe should be

A
45 mm
B
60 mm
C
75 mm
D
90 mm

Question 106Single Answer

A plane wall is 20 cm thick with an area perpendicular to heat flow of 1m²and has a thermal conductivity of 0.5 W/mK. A temperature difference 100°C is imposed across it. The rate of heat flow is

A
0.10kW
B
0.15kW
C
0.15kW
D
0.25kW

Question 107Single Answer

The laminar flow is characterized by Reynolds number which is

A
Equal to critical value
B
Less than the critical value
C
More than the critical value
D
Zero critical value

Question 108Single Answer

Consider the following statements:An increase in pin fin effectiveness is caused by high value of
1.Convective coefficient
2.Thermal conductivity
3.Sectional area
4.Circumference
Which of the above statements are correct?

A
1 and 3
B
1 and 4
C
2 and 3
D
2 and 4

Question 109Single Answer

In a laminar developing flow through a pipe with constant wall
temperature, the magnitude of the pipe wall inner surface convective heat transfer coefficient shall be maximum at the:

A
Middle length of flow
B
Beginning of flow
C
End of flow
D
None of the above

Question 110Single Answer

Oxides of nitrogen in petrol engine exhaust can be reduced by the following methods:
1.Use of 5% lean mixture
2.Advancing the spark timing
3.Recirculating a fraction of exhaust gas
4.Using an oxidation catalyst in the exhaust manifold
Which of the above statements is/are correct?

A
1 and 2
B
2 only
C
3 and 4
D
3 only

Question 111Single Answer

Consider the following statements with regard to heat transfer:
1.The temperature variation in lumped heat capacity analysis is exponential with time.
2.In situations involving simultaneous heat and mass transfer, the ratio of convective heat transfer to convective mass transfer varies with Lewis number, Le, as (Le)^1/3.
Which of the above statements are correct?

A
Both 1 and 2
B
Neither 1 nor 2
C
1 only
D
2 only

Question 112Single Answer

For a fluid with Prandtl number Pr>1, momentum boundary layer thickness

A
Decreases rapidly compared to the thermal boundary layer thickness
B
And thermal boundary layer thickness increases and same rate
C
Increases rapidly compared to the thermal boundary layer thickness
D
And thermal boundary layer thickness decreases and same rate

Question 113Single Answer

For the same type of shapes, the value of Radiation Shape Factor will be higher when the surfaces are

A
More closer only
B
Moved further apart
C
Smaller and held closer
D
Larger and held closer

Question 114Single Answer

In a pipe, laminar flow in fully developed region with constant heat flux from pipe wall, bulk mean temperature of fluid

A
And the pipe wall temperature increases in flow direction
B
And the pipe wall temperature decreases in flowdirection
C
Remains constant, but pipe wall temperature increases in flow direction
D
Increases but pipe wall temperature remains constant

Question 115Single Answer

Which of the following statements is correct for steam boiler?

A
Boiler secondary heat transfer surface includes super-heater,
economizer and air pre-heater
B
Boiler primary heat transfer surface includes evaporation section, super-heater section, reheat section
C
Boiler primary heat transfer surface includes evaporation section, economizer and super-heater section
D
Boiler secondary heat transfer surface includes evaporation section, economizer and air pre-heater

Question 116Single Answer

In a wall of constant thermal conductivity, the temperature profile for heat conduction in the presence of a heat source inside the wall is

A
Linear
B
Logarithmic
C
Parabolic
D
Hyperbolic

Question 117Single Answer

Determine the heat transfer through a plane of length 4m, height 3m and thickness 0.2 m. The temperature of inner and outer surfaces is 150°C and 90°C respectively. Thermal conductivity of the wall is 0.5 W/mK.

A
1800 W
B
2000 W
C
2200 W
D
2400 W

Question 118Single Answer

Along the ‘triple line’ in a p-v diagram showing all three phases of water, which one of the following statements is correct?

A
A substance has the same pressure and temperature but different specific volume.
B
A substance has the same temperature and specific volume but different pressure.
C
A substance has the same specific volume and pressure but different temperature.
D
A substance has the same specific volume, pressure and temperature.

Question 119Single Answer

In a cyclic process, the heat transfer are +30J, -50J, -10J and +60J. The net work for the cyclic process is

A
30Nm
B
40Nm
C
50 Nm
D
60 Nm

Question 120Single Answer

A researcher claims that he has developed an engine, which while working between source and sink temperatures of 377°C and 27°C rejects only 50% of absorbed heat. What will his engine be?

A
An impossible engine
B
A stirling engine
C
A reversible engine
D
A practical engine

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