SSC JE Mechanical 4 Dec 2023 Official Paper - II (Previous Year Paper)

Which of the following points correctly pairs boiler mountings with primary functions of boilers?

(i) Manhole - Melts and releases steam if the water level in the boiler drops too down,

(ii) Feed check valve - Prevents backflow of water into the feed pump,

(iii) Pressure gauge - Releases excess steam from the boiler to prevent overpressure,

(iv) Fusible plug - Allows the boiler to be drained for inspection and maintenance

What is the pressure increase inside a soap bubble (Δp), which has two interfaces with air, an inner and outer surface of nearly the same radius 'R' ?

(Consider that 'γ' is the coefficient of surface tension.)

The Rankine efficiency of a steam power plant:

According to laws of thermodynamics, which of the following statements is INCORRECT?

A diesel engine has a compression ratio of 15 and heat addition at a constant pressure takes place at 6% of stroke. Find the air standard efficiency of the diesel engine.

(Take γ for air = 1.4.)

Identify the correct option based on the assertion (A) and reason (R) listed below.

Assertion (A) : Dam walls are made thicker at the bottom than top.

Reason (R) : Pressure due to water is highest at the bottom.

As per the boiler regulations, every boiler must be fitted with at least ________ safety valves.

The main purpose of using the evaporator in a refrigeration system is to _______.

Select the correct option based on the assertion (A) and reason (R) listed below.

Assertion (A) : Two surfaces are polished and brought in contact with each other to reduce friction.

Reason (R) : Rough surfaces have less friction between them.

What will be the maximum coefficient of performance (COP) for the vapour absorption cycle if T_g is generator temperature, Tc is environment temperature and T_e is refrigerated space temperature?

Centrifugal pumps dealing with mud, slurry and sewage have _______.

Calculate the kinetic head (in meter) for a system wherein water is flowing through a pipe of 4 cm diameter under pressure of 20 N/cm² and mean velocity of 2 m/s. Take g = 10 m/s².

Calculate the magnitude of resultant of two like parallel forces of 20 N separated by a distance of 20 cm.

Calculate the discharge through a convergent mouthpiece of diameter 50 mm that is discharging water under a constant head of 20 meters in litre / second (Consider g = 10 m/s²)

Which of following is a defect that would never occur in shielded metal arc welding?

The velocity profile of a turbulent flow along a wall consists of four regions, characterised by the distance from the wall. The correct sequence of these regions from the wall is:

What is the maximum coefficient of performance (COP) for an absorption type refrigerator wherein heating, cooling and refrigeration occur at temperatures of 100°C, 20°C and - 5°C, respectively?

A draft tube has the inlet diameter of 1 m and the outlet diameter of 2 m. The absolute pressure at the inlet of the draft tube is 0.4 bar. The outlet of the draft tube is exposed to atmosphere. The flow rate of water through the draft tube is 1600 litres per second. Then, the vertical distance between the inlet and the outlet is approximately ________.

_______ is the pressure that a fluid attains when it is brought to rest isentropically.

A fluid cannot cross a streamline. The reason is that, at all the points, the velocity perpendicular to the streamline is _______.

Which of the following is NOT a type of centrifugal pump ?

As per the steady flow energy equation, work is done in rotary compressors due to _______.

Match column A with column B.

The sum of datum head and pressure head from Bernoulli's equation is known as ________.

A single - stage, reciprocating air compressor takes in 1.4 kg of air per minute at 1 bar and 17°C and delivers it at 6 bar. Assuming that the compression process follows the law pV^1.35 = constant, calculate the indicated power input to the compressor.

Match column A with column B.

Column A	Column B
A.		1.	Radial vanes
B.		2.	Backward curved Vanes
C.		3.	Forward curved vanes

What is the coefficient of performance (COP) of a vapour compression refrigeration system if the enthalpies at the start of compression, at the end of compression and at the end of condensation are 195 kJ/kg, 220 kJ/kg and 95 kJ/kg, respectively?

Identify the correct statement from the following.

Calculate the total head of water at the cross section of 5 m above the datum line. The pipe has a diameter of 5 cm, and the water is flowing with a pressure of 100 × 10³ N/m² and mean velocity of 2 m/s. Take g = 10 m/s².

Which of the following is NOT a method of steam turbine governing ?

Based on the following two statements related to the manometer, select the correct option.

Statements :

A) A piezometer tube can measure the pressure in a container that is lesser than the atmospheric pressure.

B) In case of a simple U - tube manometer, if the pressure to be measured is high, then a lighter gauge fluid is preferred and, if the pressure is low, a heavier gauge fluid is preferred.

Match column A with column B.

Calculate the head loss due to friction using Darcy formula when water flows through a pipe of 100 mm in diameter and 50 m long with velocity of 2 m/s. Assume f = 0.005 and g = 10 m/s².

Match the properties of fluids mentioned in Column (A) with the related parameters mentioned in Column (B).

Which of the following diagrams is that of a lobe compressor ?

The basic function of an expansion valve in a refrigerator is to ________ the _______ refrigerant from the _______ pressure to the ________ pressure.

In a steady-flow air compressor, air enters at a speed of 5 m/s with a pressure of 1 bar and leaves at a speed of 7.5 m/s with a pressure of 7 bar. If the inlet specific volume is 0.5 m³/kg and the outlet specific volume is 0.15 m³/kg, what is the ratio of the inlet pipe diameter to the outlet pipe diameter?

A mass of 2.4 kg of air at 150 kPa and 12°C is contained in a gas - tight, frictionless piston - cylinder device. The air is then compressed to a final pressure of 600 kPa. During this process, heat is transferred from the air in such a way that the temperature inside the cylinder remains constant. Calculate the work input during the process.

Free air of volumetric flow rate 30 m³/min is compressed from 101.3 kPa to 2.23 bar in a Roots blower. Determine the indicated power required.

As per the valve timing diagram of the four - stroke cycle diesel engine, typically, the fuel valve closes _______.

Among the following impeller arrangements, which impeller of the centrifugal pump offers the maximum efficiency ?

The basic difference between the reversed Carnot cycle and the ideal vapour - compression refrigeration cycle is that a/an _______ in the reversed Carnot cycle is replaced with a/an ________ in the ideal vapour - compression refrigeration cycle.

Regarding the pressure distribution of a fluid in an open rectangular tank, which of the below - mentioned statements is FALSE?

About which of the following aspects of a thermodynamic process does the first law of thermodynamics NOT provide information?

Which of the following is an INCORRECT statement?

A steel bar with the area of cross - section 500 mm² is acted upon by the forces shown in the figure below. What is the total elongation in the bar if the value of Young's modulus is 200 GPa?

Match column A with column B.

The Darcy friction factor (f) for fully developed laminar flow in a circular pipe with the Reynolds number of 1600 is given as:

Which of the following pressure measurement gauges is gravity based?

The absolute pressure is equal to:

Based on the following two statements related to the actual vapour power cycle and the ideal Rankine cycle, select the correct option.

Statements :

A) Steam leaves the boiler at a somewhat lower pressure in the actual cycle than the ideal one.

B) Water must be pumped to a sufficiently higher pressure in the actual cycle than the ideal one.

Based on the following two statements related to boilers, select the correct option.

Statements :

A) The major drawback in a LaMont boiler is formation and sticking of bubbles in the inner surface of heating tubes.

B) If the boiler pressure is raised to critical pressure, the steam and the water will have the same density and thereby, the risk of bubble formation can be eliminated.

A Carnot cycle runs between _______ adiabatic and _______ isothermal processes.

Match the thermodynamic systems with their correct examples.

Which of the following is NOT a natural circulation boiler?

In case of frictionless flow with no work or heat transfer, the height of the energy grade line (EGL) is _______ and is equal to the _______.

The shear stress at the outer surface of a solid shaft with diameter D and torque T is _______.

Darcy's friction factor for a fully developed flow through a closed duct is given by _______.

(Consider that D_h is hydraulic diameter, τ_w is wall shear stress, Δp^* is piezometric pressure drop over a length of L, ρ is density and V is average flow velocity.)

Based on the following two statements related to the pressure in a static fluid, select the correct option.

Statements:

A) Absolute pressures are always positive, but gauge pressures can be either positive or negative.

B) A gauge pressure of zero corresponds to a pressure that is below the local atmospheric pressure.

Identify the correct options based on the assertion and reason listed below.

Assertion (A) : Compounding is done in the turbine.

Reason (R) : Compounding is done to prevent over speeding of turbine.

Based on the two statements given below, select the correct option.

Statements :

A) The state of a simple compressible system is completely specified by three independent, intensive properties.

B) A system is called a simple compressible system in the absence of an electrical, magnetic, gravitational, motion or surface tension effect.

_______ pressure is measured at any point in a fluid which is non - moving.

The operation of enlarging an already drilled hole is known as _______.

What is the primary purpose of using an economiser in a boiler system ? 

Which of the following is / are the correct pair(s) of reaction turbines ?

1. Francis turbine - Mixed - flow turbine
2. Kaplan turbine - Radial flow turbine
3. Propeller turbine - Axial flow turbine

An efficient lubrication system ensures that ______.

What is the effect of increase in the evaporator temperature on the COP of a vapour compression refrigeration cycle?

Statement 1 : The coefficient of performance (COP) of a vapour compression refrigeration cycle is directly proportional to the evaporator temperature and inversely proportional to the condenser temperature.

Statement 2 : A vapour compression refrigeration cycle with a higher COP is more energy efficient.

Considering the above - mentioned question and statements, select the correct option.

The ratio of the sensible heat transfer to the total heat transfer in air - conditioning systems is known as ______.

A gaseous system having internal energy of 50 J is being added by 100 J of heat. Calculate the amount of external work done.

High carbon steels have carbon percentage in the range of:

Identify the odd one on the basis of the number of tubes.

Based on the following two statements related to the Curtis stage turbine, select the correct option.

Statements :

A) In the Curtis stage turbine, the total enthalpy and pressure drop occurs in the nozzles so that the pressure remains constant in all the three rows of blades.

B) In the fixed (static) blade passage, both pressure and velocity remain constant.

Select the correct option on the basis of the statements given below.

Statement A : Water tube boilers are low-pressure boilers.

Statement B : Fire tube boilers are high-pressure boilers.

Which of the following statements expresses the main function of a steam generator?

A cylindrical pipe of diameter 1.5 m and thickness 1.5 cm is subjected to internal fluid pressure of 1.2 N/mm². Determine the longitudinal stress developed in the pipe.

Which of the following statements is true?

Based on the two statements given below, select the correct option.

Statements :

A) The first law of thermodynamics is also known as the conservation of energy principle.

B) For all the adiabatic processes between two specified states of a closed system, the net work done is the same, regardless of the nature of the closed system and the details of the process.

Which of the following options is NOT considered as an assumption when deriving Bernoulli's equation for a fluid flow ?

The ratio of the power produced by the turbine runner to the power supplied by water at the turbine inlet is defined as _______.

Which of the following is NOT a type of oil pump used in IC engine.

Which of the following statements is INCORRECT regarding heat and work?

In the P - V diagram for a pure substance, the point at which the saturated liquid line and the saturated vapour line meet is called _______.

In the gas welding process, a neutral flame contains _______ and ________ in equal proportions.

Surface tension can also be expressed as ______.

The specific gravity of a fluid is 0.8. What is its specific weight at 4°C?

Which of the following is NOT a boiler accessory?

Which of the following options represents the correct order of flow of water in the power conversion of the Pelton wheel turbine?

In the winter air-conditioning, for comfort, moisture is added without changing its dry bulb temperature and the air is made to warm up. Identify the type of process.

Which of the following statements is INCORRECT regarding a thermodynamic system?

Isochoric process means:

In a fluid flow, if the inertia forces are very large as compared to the viscous force, then the type of flow of fluid is called _______.

In an engine cooling system, the _______ spread(s) the hot water over a large area.

Considering a grinding wheel and a regulating wheel in regard to the centreless grinding machine working principle, the ________ is of greater diameter and has a high rotational speed, whereas the _______ is of smaller diameter and has a low speed.

A single-stage, reciprocating air compressor is required to compress 1 kg of air from 1 bar to 4 bar. The initial temperature is 27°C. Select the correct option.

(Given, W = Work required for isothermal compression, W_poly = Work required for polytropic compression (pv^1.2 = Constant) and W_isen = Work required for isentropic compression)

What will be the brake power (BP) of the engine if it is tested with a rope brake dynamometer?

Given, W = Dead load (in Newtons), S = Spring balance reading (in Newtons), D = Diameter of the wheel (in metres), d = Diameter of the rope (in metres) and N = Speed of the engine shaft (in RPM)

The flywheel of a steam engine has a radius of gyration 1 m and mass of 3000 kg. The starting torque of the engine is 3000 N - m. The kinetic energy of such a flywheel after 10 sec from rest position will be _______.

The law of thermodynamics that hints at the fact that no heat engine can have efficiency equal to 100% is the

The Rankine cycle comprises:

Which of the following is a boiler accessory?

Identify the cycle on the basis of the T-S diagram shown below.