Recent questions in Applications / GO Mechanical

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GATE2016-3-46
In a $3$-stage air compressor, the inlet pressure is $p_1$, discharge pressure is $p_4$.and the intermediate pressures are $p_2$ and $p_3 ( p_2 < p_3)$. The total pressure ratio of the compressor is $10$ and the pressure ratios of the stages are equal. If $p_1 = 100$ $kPa$, the value of the pressure $p_3$ (in $kPa$) is __________

In a $3$-stage air compressor, the inlet pressure is $p_1$, discharge pressure is $p_4$.and the intermediate pressures are $p_2$ and $p_3 ( p_2 < p_3)$. The total pressur...

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GATE2016-3-45
In a mixture of dry air and water vapor at a total pressure of $750$ $mm$ of $Hg$, the partial pressure of water vapor is $20$ $mm$ of $Hg$. The humidity ratio of the air in grams of water vapor per $kg$ of dry air ($g_w/kg_{da}$) is __________

In a mixture of dry air and water vapor at a total pressure of $750$ $mm$ of $Hg$, the partial pressure of water vapor is $20$ $mm$ of $Hg$. The humidity ratio of the air...

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GATE2016-3-19
The blade and fluid velocities for an axial turbine are as shown in the figure. The magnitude of absolute velocity at entry is $300$ $m/s$ at an angle of $65^\circ$ to the axial direction, while the magnitude of the absolute velocity at exit is ... downward direction. Given that the axial (horizontal) velocity is the same at entry and exit, the specific work (in $kJ/kg$) is__________

The blade and fluid velocities for an axial turbine are as shown in the figure.The magnitude of absolute velocity at entry is $300$ $m/s$ at an angle of $65^\circ$ to the...

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GATE2016-2-47
The partial pressure of the water vapour in a moist air sample of relative humidity $70\%$ is $1.6 \: kPa$,the total pressure being $101.35 \: kPa$ ... where $p_o=101.325 \: kPa$. The dry bulb temperature of the moist air sample (in $_{}^{\circ}\textrm{C}$) is

The partial pressure of the water vapour in a moist air sample of relative humidity $70\%$ is $1.6 \: kPa$,the total pressure being $101.35 \: kPa$.moist air may be treat...

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GATE2016-2-46
A refrigerator uses $R-134a$ as its refrigerant and operates on an ideal vapour-compression refrigeration cycle between $0.14 \: MPa$ and $0.8 \: MPa$.if the mass flow rate of refrigerant is $0.05 \: kg/s$,the rate of heat rejection to the environment is_______$kW$ ... $\text{At } P=0.8 \: MPa, \: h=93.42 \: kJ/kg, \: \text{ (saturated liquid) }$

A refrigerator uses $R-134a$ as its refrigerant and operates on an ideal vapour-compression refrigeration cycle between $0.14 \: MPa$ and $0.8 \: MPa$.if the mass flow ra...

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GATE2016-2-19
Consider a simple gas turbine (Brayton) cycle and a gas turbine cycle with perfect regeneration. In both the cycles, the pressure ratio is $6$ and the ratio of the specific heats of the working medium is $1.4$. The ratio of minimum to maximum ... $K$) in the regenerative cycle. The ratio of the thermal efficiency of the simple cycle to that of the regenerative cycle is _________

Consider a simple gas turbine (Brayton) cycle and a gas turbine cycle with perfect regeneration. In both the cycles, the pressure ratio is $6$ and the ratio of the specif...

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GATE2016-2-18
The heat removal rate from a refrigerated space and the power input to the compressor are $7.2$ $kW$ and $1.8$ $kW$, respectively. The coefficient of performance (COP) of the refrigerator is ______

The heat removal rate from a refrigerated space and the power input to the compressor are $7.2$ $kW$ and $1.8$ $kW$, respectively. The coefficient of performance (COP) of...

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GATE2016-2-14
Assuming constant temperature condition and air to be an ideal gas, the variation in atmospheric pressure with height calculated from fluid statics is linear exponential quadratic cubic

Assuming constant temperature condition and air to be an ideal gas, the variation in atmospheric pressure with height calculated from fluid statics islinearexponentialqua...

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GATE2016-1-47
In a steam power plant operating on an ideal Rankine cycle, superheated steam enters the turbine at $3 \: MPa$ and $350^ \circ C$. The condenser pressure is $75$ $kPa$. The thermal efficiency of the cycle is ________ percent. Given data: For saturated liquid, at $P=75 \:kPa$ ... $T=350^\circ C$ (superheated steam), $h=3115.3 \: kJ/kg$, $s=6.7428 \: kJ/kg-K$

In a steam power plant operating on an ideal Rankine cycle, superheated steam enters the turbine at$3 \: MPa$ and $350^ \circ C$. The condenser pressure is $75$ $kPa$. Th...

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GATE2016-1-46
An ideal gas undergoes a reversible process in which the pressure varies linearly with volume. The conditions at the start (subscript $1$) and at the end (subscript $2$) of the process with usual notation are: $p_1 = 100 \: kPa$, $V_1 = 0.2 \: m^3$ ... $R=0.275\:kJ/kg-K$. The magnitude of the work required for the process (in $kJ$) is ________

An ideal gas undergoes a reversible process in which the pressure varies linearly with volume. The conditions at the start (subscript $1$) and at the end (subscript $2$) ...

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GATE2016-1-20
The “Jominy test” is used to find Young’s modulus hardenability yield strength thermal conductivity

The “Jominy test” is used to findYoung’s modulushardenabilityyield strengththermal conductivity

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GATE2016-1-19
The INCORRECT statement about regeneration in vapor power cycle is that it increases the irreversibility by adding the liquid with higher energy content to the steam generator heat is exchanged between the expanding fluid in the turbine and the compressed ... the principle is similar to the principle of Stirling gas cycle it is practically implemented by providing feed water heaters

The INCORRECT statement about regeneration in vapor power cycle is thatit increases the irreversibility by adding the liquid with higher energy content to the steam gener...

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GATE2016-1-18
Consider two hydraulic turbines having identical specific speed and effective head at the inlet. If the speed ratio $\displaystyle{\left(\frac{N_1}{N_2}\right)}$ of the two turbines is $2$, then the respective power ratio $\displaystyle{\left(\frac{P_1}{P_2}\right)}$ is _____________

Consider two hydraulic turbines having identical specific speed and effective head at the inlet. If the speed ratio $\displaystyle{\left(\frac{N_1}{N_2}\right)}$ of the t...

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GATE2015-3-52
Which of the following statements are TRUE, when the cavitation parameter $\sigma =0$? the local pressure is reduced to vapor pressure cavitation starts boiling of liquid starts cavitation stops (i), (ii) and (iv) only (ii) and (iii) only (i) and (iii) (i), (ii) and (iii)

Which of the following statements are TRUE, when the cavitation parameter $\sigma =0$?the local pressure is reduced to vapor pressurecavitation startsboiling of liquid st...

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GATE2015-3-47
The torque (in $N$-$m$) exerted on the crank shaft of a two stroke engine can be described as $T = 10000 + 1000 \sin(2θ) − 1200 \cos(2θ)$, where $θ$ is the crank angle as measured from inner dead center position. Assuming the resisting torque to be constant, the power (in $kW$) developed by the engine at $100$ $rpm$ is ________

The torque (in $N$-$m$) exerted on the crank shaft of a two stroke engine can be described as $T = 10000 + 1000 \sin(2θ) − 1200 \cos(2θ)$, where $θ$ is the crank ang...

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GATE2015-3-45
A bullet spins as the shot is fired from a gun. For this purpose, two helical slots as shown in the figure are cut in the barrel. Projections $A$ and $B$ on the bullet engage in each of the slots. Helical slots are such that one turn of helix is completed over a ... $m$. If velocity of bullet when it exits the barrel is $20$ $m/s$, its spinning speed in $rad/s$ is ________

A bullet spins as the shot is fired from a gun. For this purpose, two helical slots as shown in the figure are cut in the barrel. Projections $A$ and $B$ on the bullet en...

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GATE2015-3-39
Air in a room is at $35^\circ C$ and $60 \%$ relative humidity (RH). The pressure in the room is $0.1 \: MPa$. The saturation pressure of water at $35^ \circ C$ is $5.63 kPa$. The humidity ratio of the air (in $gram/kg$ of dry air) is ________

Air in a room is at $35^\circ C$ and $60 \%$ relative humidity (RH). The pressure in the room is $0.1 \: MPa$. The saturation pressure of water at $35^ \circ C$ is $5.63...

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GATE2015-3-37
Refrigerant vapor enters into the compressor of a standard vapor compression cycle at −$10^\circ C \:(h = 402 \: kJ/kg)$ and leaves the compressor at $50^\circ C \: (h = 432 \: kJ/kg)$. It leaves the condenser at $30^\circ C \: (h = 237 \: kJ/kg)$. The COP of the cycle is ________

Refrigerant vapor enters into the compressor of a standard vapor compression cycle at −$10^\circ C \:(h = 402 \: kJ/kg)$ and leaves the compressor at $50^\circ C \: (h ...

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GATE2015-3-38
Steam enters a turbine at $30$ bar, $300^\circ C \: (u = 2750 \: kJ/kg$, $h = 2993 \: kJ/kg)$ and exits the turbine as saturated liquid at $15 \: kPa \: (u = 225 \: kJ/kg$, $h = 226 \: kJ/kg)$. Heat loss to the ... $kJ/kg$ of steam) is ________

Steam enters a turbine at $30$ bar, $300^\circ C \: (u = 2750 \: kJ/kg$, $h = 2993 \: kJ/kg)$ and exits the turbine as saturated liquid at $15 \: kPa \: (u = 225 \: kJ/kg...

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GATE2015-3-25
An air-standard Diesel cycle consists of the following processes: $1 - 2$: Air is compressed isentropically. $2 - 3$: Heat is added at constant pressure. $3 - 4$: Air expands isentropically to the original volume. $4 - 1$: Heat is rejected at constant volume. If $\gamma$ ... $1-\displaystyle{\frac{T_4-T_1}{(\gamma -1)(T_3-T_2)}}$

An air-standard Diesel cycle consists of the following processes:$1 – 2$: Air is compressed isentropically.$2 – 3$: Heat is added at constant pressure.$3 – 4$: Air ...

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GATE2015-2-53
A resistance-capacitance relaxation circuit is used in an electrical discharge machining process. The discharge voltage is $100$ $V$. At a spark cycle time of $25$ $μs$, the average power input required is $1$ $kW$. The capacitance (in $μF$) in the circuit is $2.5$ $5.0$ $7.5$ $10.0$

A resistance-capacitance relaxation circuit is used in an electrical discharge machining process. The discharge voltage is $100$ $V$. At a spark cycle time of $25$ $μs$,...

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GATE2015-2-47
In a Rankine cycle, the enthalpies at turbine entry and outlet are $3159$ $kJ/kg$ and $2187$ $kJ/kg$, respectively. If the specific pump work is $2$ $kJ/kg$, the specific steam consumption (in $kg/kW$-$h$) of the cycle based on net output is _______________

In a Rankine cycle, the enthalpies at turbine entry and outlet are $3159$ $kJ/kg$ and $2187$ $kJ/kg$, respectively. If the specific pump work is $2$ $kJ/kg$, the specific...

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GATE2015-2-45
One kg of air ($R=287 \: J/kg – K$) undergoes an irreversible process between equilibrium state $1(20^{\circ}C$, $0.9 \: m^3$) and equilibrium state $2 ( 20^{\circ} C$, $0.6\: m^3$). The change in entropy $s_2 – s_1$ (in $J/kg – K$) is _______

One kg of air ($R=287 \: J/kg – K$) undergoes an irreversible process between equilibrium state $1(20^{\circ}C$, $0.9 \: m^3$) and equilibrium state $2 ( 20^{\circ} C$,...

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GATE2015-2-39
The total emissive power of a surface is $500 \: W/ m^2$ at a temperature $T_1$ and $1200 \: W/m^2$ at a temperature $T_2$, where the temperatures are in Kelvin. Assuming the emissivity of the surface to be constant, the ratio of the temperatures $\dfrac{T_1}{T_2}$ is $0.308$ $0.416$ $0.803$ $0.874$

The total emissive power of a surface is $500 \: W/ m^2$ at a temperature $T_1$ and $1200 \: W/m^2$ at a temperature $T_2$, where the temperatures are in Kelvin. Assuming...

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GATE2015-2-18
The Van der Waals equation of state is $(p+\dfrac{a}{v^2})(v-b)=RT$ where $p$ is pressure, $v$ is specific volume, $T$ is temperature and $R$ is characteristic gas constant. The SI unit of $a$ is $J/kg – K $ $m^3/kg$ $m^5/kg-s^2$ $Pa/kg$

The Van der Waals equation of state is $(p+\dfrac{a}{v^2})(v-b)=RT$ where $p$ is pressure, $v$ is specific volume, $T$ is temperature and $R$ is characteristic gas const...

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GATE2015-2-17
The COP of a Carnot heat pump operating between $6^{\circ}C$ and $37^{\circ}C$ is ___________

The COP of a Carnot heat pump operating between $6^{\circ}C$ and $37^{\circ}C$ is ___________

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GATE2015-2-16
In the laminar flow of air ($P_r$ = $0.7$) over a heated plate, if $\delta$ and $\delta _T$ denote, respectively, the hydrodynamic and thermal boundary layer thicknesses, then $\delta =\delta _T$ $\delta > \delta _T$ $\delta < \delta _T$ $\delta =0$ but $\delta _T\neq 0$

In the laminar flow of air ($P_r$ = $0.7$) over a heated plate, if $\delta$ and $\delta _T$ denote, respectively, the hydrodynamic and thermal boundary layer thicknesses,...

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GATE2015-1-55
Steam enters a well insulated turbine and expands isentropically throughout. At an intermediate pressure, $20$ percent of the mass is extracted for process heating and the remaining steam expands isentropically to $9 \: kPa$ ... If the flow rate of steam entering the turbine is $100$ $kg/s$, then the work output (in $MW$) is _________

Steam enters a well insulated turbine and expands isentropically throughout. At an intermediate pressure, $20$ percent of the mass is extracted for process heating and th...

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GATE2015-1-54
A well insulated rigid container of volume $1 \: m^3$ contains $1.0 \: kg$ of an ideal gas $[C_p = 1000 \: J/(kg\cdot K)$ and $C_v=800 J/(kg \cdot K)]$ at a pressure of $105 \: Pa$. A stirrer is rotated at constant rpm in the container for $1000$ rotations and the applied torque is $100 \: N-m$. The final temperature of the gas (in $K$) is $500.0$ $773.0$ $785.4$ $1285.4$

A well insulated rigid container of volume $1 \: m^3$ contains $1.0 \: kg$ of an ideal gas $[C_p = 1000 \: J/(kg\cdot K)$ and $C_v=800 J/(kg \cdot K)]$ at a pressure of ...

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GATE2015-1-12
A stream of moist air (mass flow rate $= 10.1 \: kg/s$) with humidity ratio of $0.01 \: \dfrac{kg}{\text{kg dry air}}$ mixes with a second stream of superheated water vapour flowing at $0.1 \: \text{kg/s}$. Assuming proper and uniform mixing with no condensation, the humidity ratio of the final stream $\big($in $\dfrac{kg}{\text{kg dry air}} \big )$ is _____________

A stream of moist air (mass flow rate $= 10.1 \: kg/s$) with humidity ratio of $0.01 \: \dfrac{kg}{\text{kg dry air}}$ mixes with a second stream of superheated water va...

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GATE2015-1-11
Air enters a diesel engine with a density of $1.0$ $kg$/$m^3$. The compression ratio is $21$. At steady state, the air intake is $30 × 10^{-3}$ $kg/s$ and the net work output is $15$ $kW$. The mean effective pressure (in $kPa$) is ____________

Air enters a diesel engine with a density of $1.0$ $kg$/$m^3$. The compression ratio is $21$. At steady state, the air intake is $30 × 10^{-3}$ $kg/s$ and the net work o...

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GATE2015-1-10
A Carnot engine ($CE_1$) works between two temperature reservoirs $A$ and $B$, where $T_A$ = $900$ $K$ and $T_B$ = $500$ $K$. A second Carnot engine ($CE_2$) works between temperature reservoirs $B$ and $C$, where $T_C$ = $300$ $K$ ... $CE_1$ from reservoir $A$ is $150$ $MJ$, the net heat rejected to reservoir $C$ by $CE_2$ (in $MJ$) is ______________

A Carnot engine ($CE_1$) works between two temperature reservoirs $A$ and $B$, where $T_A$ = $900$ $K$ and $T_B$ = $500$ $K$. A second Carnot engine ($CE_2$) works betwee...

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GATE Mechanical 2014 Set 4 | Question: 49
In a compression ignition engine, the inlet air pressure is $1$ bar and the pressure at the end of isentropic compression is $32.42$ bar. The expansion ratio is $8$. Assuming ratio of specific heats $(γ)$ as $1.4$, the air standard efficiency (in percent) is _______

In a compression ignition engine, the inlet air pressure is $1$ bar and the pressure at the end of isentropic compression is $32.42$ bar. The expansion ratio is $8$. Assu...

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GATE Mechanical 2014 Set 4 | Question: 47
Steam with specific enthalpy $(h)$ $3214$ $kJ/kg$ enters an adiabatic turbine operating at steady state with a flow rate $10$ $kg/s$. As it expands, at a point where h is $2920$ $kJ/kg$, $1.5$ $kg/s$ is extracted for heating ... = $2374$ $kJ/kg$. Neglecting changes in kinetic and potential energies, the net power output (in $kW$) of the turbine is _______

Steam with specific enthalpy $(h)$ $3214$ $kJ/kg$ enters an adiabatic turbine operating at steady state with a flow rate $10$ $kg/s$. As it expands, at a point where h is...

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GATE Mechanical 2014 Set 4 | Question: 16
Kaplan water turbine is commonly used when the flow through its runner is axial and the head available is more than $100$ $m$ axial and the head available is less than $10$ $m$ radial and the head available is more than $100$ $m$ mixed and the head available is about $50$ $m$

Kaplan water turbine is commonly used when the flow through its runner isaxial and the head available is more than $100$ $m$axial and the head available is less than $10$...

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GATE Mechanical 2014 Set 4 | Question: 13
A reversed Carnot cycle refrigerator maintains a temperature of −$5^{\circ}$ $C$. The ambient air temperature is $35^{\circ}$ $C$. The heat gained by the refrigerator at a continuous rate is $2.5$ kJ/s. The power (in watt) required to pump this heat out continuously is _______

A reversed Carnot cycle refrigerator maintains a temperature of −$5^{\circ}$ $C$. The ambient air temperature is $35^{\circ}$ $C$. The heat gained by the refrigerator a...

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GATE Mechanical 2014 Set 4 | Question: 12
As the temperature increases, the thermal conductivity of a gas increases decreases remains constant increases up to a certain temperature and then decreases

As the temperature increases, the thermal conductivity of a gas increasesdecreasesremains constantincreases up to a certain temperature and then decreases

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GATE Mechanical 2014 Set 3 | Question: 49
A diesel engine has a compression ratio of $17$ and cut-off takes place at $10\%$ of the stroke.Assuming ratio of specific heats $(\gamma)$ as $1.4$, the air-standard efficiency (in percent) is _______

A diesel engine has a compression ratio of $17$ and cut-off takes place at $10\%$ of the stroke.Assuming ratio of specific heats $(\gamma)$ as $1.4$, the air-standard eff...

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GATE Mechanical 2014 Set 3 | Question: 41
A certain amount of an ideal gas is initially at a pressure $p_1$ and temperature $T_1$. First, it undergoes a constant pressure process $1$-$2$ such that $T_2$ = $3T_1$/$4$. Then, it undergoes a constant volume process $2$-$3$ such that $T_3$ = $T_1$/$2$. The ratio of the final volume to the initial volume of the ideal gas is $0.25$ $0.75$ $1.0$ $1.5$

A certain amount of an ideal gas is initially at a pressure $p_1$ and temperature $T_1$. First, it undergoes a constant pressure process $1$-$2$ such that $T_2$ = $3T_1$/...

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GATE Mechanical 2014 Set 3 | Question: 46
At the inlet of an axial impulse turbine rotor, the blade linear speed is $25 \: m/s$, the magnitude of absolute velocity is $100 \: m/s$ and the angle between them is $25^{\circ}$. The relative velocity and the axial component ... blade inlet and outlet velocity triangles are shown in the figure. Assuming no losses, the specific work (in $J/kg$) is _______

At the inlet of an axial impulse turbine rotor, the blade linear speed is $25 \: m/s$, the magnitude of absolute velocity is $100 \: m/s$ and the angle between them is $2...

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