Most viewed questions in Fluid Mechanics and Thermal Sciences / GO Mechanical

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GATE2015-2-15
If a foam insulation is added to a $4 \: cm$ outer diameter pipe as shown in the figure, the critical radius of insulation (in $cm$) is _____________

If a foam insulation is added to a $4 \: cm$ outer diameter pipe as shown in the figure, the critical radius of insulation (in $cm$) is _____________

Arjun

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GATE Mechanical 2014 Set 3 | Question: 16
A source at a temperature of $500$ $K$ provides $1000$ $kJ$ of heat. The temperature of environment is $27^oC$. The maximum useful work (in $kJ$) that can be obtained from the heat source is _______

A source at a temperature of $500$ $K$ provides $1000$ $kJ$ of heat. The temperature of environment is $27^oC$. The maximum useful work (in $kJ$) that can be obtained fro...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 2 | Question: 44
A material P of thickness $1$ $mm$ is sandwiched between two steel slabs, as shown in the figure below. A heat flux $10$ $kW/m^2$ is supplied to one of the steel slabs as shown. The boundary temperatures of the slabs are indicated ... steady state heat conduction for the configuration, the thermal conductivity ($k$, in $W/m.K$) of material $P$ is _______

A material P of thickness $1$ $mm$ is sandwiched between two steel slabs, as shown in the figure below. A heat flux $10$ $kW/m^2$ is supplied to one of the steel slabs as...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 1 | Question: 15
For a completely submerged body with Centre of gravity ‘G’ and Centre of buoyancy ‘B’, the condition of stability will be G is located below B G is located above B G and B are coincident independent of the locations of G and B

For a completely submerged body with Centre of gravity ‘G’ and Centre of buoyancy ‘B’, the condition of stability will beG is located below BG is located above BG...

Arjun

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Arjun asked Feb 19, 2017

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ISRO2009-5
Across a normal shock Static pressure and the static temperature rise entropy remains constant velocity and static pressure decrease density and temperature decrease

Across a normal shockStatic pressure and the static temperature riseentropy remains constantvelocity and static pressure decreasedensity and temperature decrease

m2n037

940 points

m2n037 asked Mar 6, 2018

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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...

Arjun

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Arjun asked Feb 24, 2017

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GATE2016-3-13
A channel of width $450$ $mm$ branches into two sub-channels having width $300$ $mm$ and $200$ $mm$ as shown in figure. If the volumetric flow rate (taking unit depth) of an incompressible flow through the main channel is $0.9$ $m^3/s$ and the velocity ... velocity in the sub-channel of width $300$ $mm$ is _____________ $m/s$. Assume both inlet and outlet to be at the same elevation.

A channel of width $450$ $mm$ branches into two sub-channels having width $300$ $mm$ and $200$ $mm$ as shown in figure. If the volumetric flow rate (taking unit depth) of...

Arjun

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Arjun asked Feb 24, 2017

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GATE2015-1-13
A wheel of radius $r$ rolls without slipping on a horizontal surface shown below. If the velocity of point $P$ is $10$ $m/s$ in the horizontal direction, the magnitude of velocity of point $Q$ (in $m/s$) is ______

A wheel of radius $r$ rolls without slipping on a horizontal surface shown below. If the velocity of point $P$ is $10$ $m/s$ in the horizontal direction, the magnitude of...

Arjun

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Arjun asked Feb 24, 2017

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GATE2016-2-45
A reversible cycle receives $40 \: kJ$ of heat from one heat source at a temperature of $127^ \circ C$ and $37 \: kJ$ from another heat source at $97^ \circ C$. The heat rejected (in $kJ$) to the heat sink at $47^ \circ C$ is __________

A reversible cycle receives $40 \: kJ$ of heat from one heat source at a temperature of $127^ \circ C$ and $37 \: kJ$ from another heat source at $97^ \circ C$. The heat ...

Arjun

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Arjun asked Feb 24, 2017

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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...

Arjun

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Arjun asked Feb 24, 2017

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GATE2015-3-12
Saturated vapor is condensed to saturated liquid in a condenser. The heat capacity ratio is $C_r = \displaystyle{\frac{C_{\text{min}}}{C_{\text{max}}}}$. The effectiveness $(\varepsilon)$ of the condenser is $\displaystyle{\frac{1-\text{exp}[-NTU(1+C_r)]}{1+C_r}} \\$ ... $\displaystyle{\frac{NTU}{1+NTU}} \\$ $1 - \text{exp}(-NTU)$

Saturated vapor is condensed to saturated liquid in a condenser. The heat capacity ratio is $C_r = \displaystyle{\frac{C_{\text{min}}}{C_{\text{max}}}}$. The effectivenes...

Arjun

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Arjun asked Feb 24, 2017

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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...

Arjun

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Arjun asked Feb 24, 2017

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GATE Mechanical 2014 Set 2 | Question: 14
For an incompressible flow field, $\overrightarrow{V}$, which one of the following conditions must be satisfied? $\bigtriangledown \cdot \overrightarrow{V}=0$ $\bigtriangledown \times \overrightarrow{V}=0$ ... $\frac{\partial \overrightarrow{V}}{\partial t}+(\overrightarrow{V} \cdot \bigtriangledown) \overrightarrow{V}=0$

For an incompressible flow field, $\overrightarrow{V}$, which one of the following conditions must be satisfied?$\bigtriangledown \cdot \overrightarrow{V}=0$$\bigtriangle...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 1 | Question: 48
A reversible heat engine receives $2$ $kJ$ of heat from a reservoir at $1000$ $K$ and a certain amount of heat from a reservoir at $800$ $K$. It rejects $1$ $kJ$ of heat to a reservoir at $400$ $K$. The net work output (in $kJ$) of the cycle is $0.8$ $1.0$ $1.4$ $2.0$

A reversible heat engine receives $2$ $kJ$ of heat from a reservoir at $1000$ $K$ and a certain amount of heat from a reservoir at $800$ $K$. It rejects $1$ $kJ$ of heat ...

Arjun

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Arjun asked Feb 19, 2017

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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 $T_2$ = $3T_1$/...

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 2 | Question: 17
The difference in pressure (in $N/m^2$) across an air bubble of diameter $0.001$ $m$ immersed in water (surface tension $= 0.072$ $N/m$) is _______

The difference in pressure (in $N/m^2$) across an air bubble of diameter $0.001$ $m$ immersed in water (surface tension $= 0.072$ $N/m$) is _______

Arjun

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Arjun asked Feb 19, 2017

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GATE2016-2-16
Consider the radiation heat exchange inside an annulus between two very long concentric cylinders. The radius of the outer cylinder is $R_o$ and that of the inner cylinder is $R_i$ . The radiation view factor of the outer cylinder onto itself is $1-\sqrt{\dfrac{R_i}{R_o}}\\$ $\sqrt{1-\dfrac{R_i}{R_o}} \\$ $1-\dfrac{R_i}{R_o}^{1/3} \\$ $1-\dfrac{R_i}{R_o}$

Consider the radiation heat exchange inside an annulus between two very long concentric cylinders. The radius of the outer cylinder is $R_o$ and that of the inner cylinde...

Arjun

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Arjun asked Feb 24, 2017

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GATE2016-1-49
Heat is removed from a molten metal of mass $2$ $kg$ at a constant rate of $10$ $kW$ till it is completely solidified.The cooling curve is shown in the figure Assuming uniform temperature throughout the volume of the metal during solidification,the latent heat of fusion of metal ( in $kJ$/$kg$) is _________

Heat is removed from a molten metal of mass $2$ $kg$ at a constant rate of $10$ $kW$ till it is completely solidified.The cooling curve is shown in the figureAssuming uni...

Arjun

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Arjun asked Feb 24, 2017

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GATE2015-1-8
For flow of viscous fluid over a flat plate, if the fluid temperature is the same as the plate temperature, the thermal boundary layer is thinner than the velocity boundary layer thicker than the velocity boundary layer of the same thickness as the velocity boundary layer not formed at all

For flow of viscous fluid over a flat plate, if the fluid temperature is the same as the plate temperature, the thermal boundary layer isthinner than the velocity boundar...

Arjun

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Arjun asked Feb 24, 2017

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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

Arjun

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Arjun asked Feb 19, 2017

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GATE Mechanical 2014 Set 3 | Question: 45
A fluid of dynamic viscosity $2 × 10^{−5}$ $kg/m.s$ and density $1$ $kg/m^3$ flows with an average velocity of $1$ $m/s$ through a long duct of rectangular ($25$ $mm$ × $15$ $mm$) cross-section. Assuming laminar flow, the pressure drop (in $Pa$) in the fully developed region per meter length of the duct is _______

A fluid of dynamic viscosity $2 × 10^{−5}$ $kg/m.s$ and density $1$ $kg/m^3$ flows with an average velocity of $1$ $m/s$ through a long duct of rectangular ($25$ $mm$ ...

Arjun

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Arjun asked Feb 19, 2017

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GATE2016-3-18
For a heat exchanger, $\triangle T_{\text{max}}$ is the maximum temperature difference and $\triangle T_{\text{min}}$ is the minimum temperature difference between the two fluids. LMTD is the log mean temperature difference. $C_{\text{min}}$ and $C_{\text{max}}$ are the minimum ... $C_{\text{max}} \triangle T_{\text{max}}$ $C_{\text{max}} \triangle T_{\text{min}}$

For a heat exchanger, $\triangle T_{\text{max}}$ is the maximum temperature difference and $\triangle T_{\text{min}}$ is the minimum temperature difference between the tw...

Arjun

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Arjun asked Feb 24, 2017

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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...

Arjun

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Arjun asked Feb 24, 2017

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GATE Mechanical 2014 Set 2 | Question: 13
The thermal efficiency of an air-standard Brayton cycle in terms of pressure ratio $r_p$ and $\gamma (= c_p /c_v)$ is given by $1-\dfrac{1}{{r_p}^{\gamma -1}} \\$ $1-\dfrac{1}{{r_p}^{\gamma }} \\$ $1-\dfrac{1}{{r_p}^{1/\gamma }} \\$ $1-\dfrac{1}{{r_p}^{(\gamma -1)/\gamma }}$

The thermal efficiency of an air-standard Brayton cycle in terms of pressure ratio $r_p$ and $\gamma (= c_p /c_v)$ is given by$1-\dfrac{1}{{r_p}^{\gamma -1}} \\$$1-\dfrac...

Arjun

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Arjun asked Feb 19, 2017

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Entroy:-why entropy generation is a an path function

Nick2277

120 points

Nick2277 asked Feb 25, 2021

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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...

Arjun

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Arjun asked Feb 24, 2017

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GATE2016-2-35
A circular metallic rod of length $250 \: mm$ is placed between two rigid immovable walls as shown in the figure. The rod is in perfect contact with the wall on the left side and there is a gap of $0.2 \: mm$ between the rod and the wall on the right side. If the ... material of the rod is $200 \: GPa$ and the coefficient of thermal expansion is $10^{−5}$ per $_{}^{\circ}\textrm{C}$.

A circular metallic rod of length $250 \: mm$ is placed between two rigid immovable walls as shown in the figure. The rod is in perfect contact with the wall on the left ...

Arjun

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Arjun asked Feb 24, 2017

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GATE2015-2-12
If the fluid velocity for a potential flow is given by $V(x,y)=u(x,y)i+v(x,y)j$ with usual notations, then the slope of the potential line at $(x,y)$ is $\dfrac{v}{u} \\$ $-\dfrac{u}{v} \\$ $\dfrac{u^2}{v^2} \\$ $\dfrac{u}{v}$

If the fluid velocity for a potential flow is given by $V(x,y)=u(x,y)i+v(x,y)j$ with usual notations, then the slope of the potential line at $(x,y)$ is$\dfrac{v}{u} \\$$...

Arjun

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Arjun asked Feb 24, 2017

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GATE2016-3-42
Two large parallel plates having a gap of $10 \: mm$ in between them are maintained at temperatures $T_1 = 1000 \: K$ and $T_2 = 400 \: K$. Given emissivity values, $\epsilon _1 = 0.5$, $\epsilon _2=0.25$ and Stefan-Boltzmann constant $\sigma =5.67 \times 10^{−8} \: W/m^2-K^4$, the heat transfer between the plates (in $kW/m^2$) is __________

Two large parallel plates having a gap of $10 \: mm$ in between them are maintained at temperatures $T_1 = 1000 \: K$ and $T_2 = 400 \: K$. Given emissivity values, $\ep...

Arjun

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Arjun asked Feb 24, 2017

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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...

Arjun

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Arjun asked Feb 24, 2017

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GATE2015-3-9
Couette flow is characterized by steady, incompressible, laminar flow through a straight circular pipe fully developed turbulent flow through a straight circular pipe steady, incompressible, laminar flow between two fixed parallel plates steady, incompressible, laminar flow between one fixed plate and the other moving with a constant velocity

Couette flow is characterized bysteady, incompressible, laminar flow through a straight circular pipefully developed turbulent flow through a straight circular pipesteady...

Arjun

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Arjun asked Feb 24, 2017

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GATE2015-1-48
Match the following pairs: \begin{array}{|l|l|l|l|} \hline &\textbf{Equation} && \textbf{Physical Interpretation} \\ \hline P. & \nabla \times \overrightarrow{V}=0 & I. & \text{ Incompressible continuity equation} \\ \hline Q. & \nabla \bullet \overrightarrow{V}=0 & II. ... $P-IV, Q-III, R-I, S-II$ $P-III, Q-I, R-IV, S-II$ $P-III, Q-I, R-II, S-IV$

Match the following pairs:\begin{array}{|l|l|l|l|} \hline &\textbf{Equation} && \textbf{Physical Interpretation} \\ \hline P. & \nabla \times \overrightarrow{V}=0 & I. & ...

Arjun

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Arjun asked Feb 24, 2017

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GATE2015-1-49
The velocity field of an incompressible flow is given by $V=(a_1x+a_2y+a_3z)i+(b_1x+b_2y+b_3z)j+(c_1x+c_2y+c_3z)z$, where $a_1$ = $2$ and $c_3$ = − $4$. The value of $b_2$ is ___________

The velocity field of an incompressible flow is given by $V=(a_1x+a_2y+a_3z)i+(b_1x+b_2y+b_3z)j+(c_1x+c_2y+c_3z)z$, where $a_1$ = $2$ and $c_3$ = − $4$. The value of $b...

Arjun

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Arjun asked Feb 24, 2017

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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...

Arjun

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Arjun asked Feb 24, 2017

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GATE2015-1-6
Consider fully developed flow in a circular pipe with negligible entrance length effects. Assuming the mass flow rate, density and friction factor to be constant, if the length of the pipe is doubled and the diameter is halved, the head loss due to friction will increase by a factor of $4$ $16$ $32$ $64$

Consider fully developed flow in a circular pipe with negligible entrance length effects. Assuming the mass flow rate, density and friction factor to be constant, if the ...

Arjun

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Arjun asked Feb 24, 2017

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GATE2016-3-14
For a certain two-dimensional incompressible flow, velocity field is given by $2xy\hat{i}-y^2\hat{j}$ . The streamlines for this flow are given by the family of curves $x^2y^2 = \text{constant}$ $xy^2 = \text{constant}$ $2xy − y^2 \text{constant}$ $xy = \text{constant}$

For a certain two-dimensional incompressible flow, velocity field is given by $2xy\hat{i}-y^2\hat{j}$ . The streamlines for this flow are given by the family of curves$...

Arjun

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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...

Arjun

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GATE2015-1-9
For an ideal gas with constant values of specific heats, for calculation of the specific enthalpy, it is sufficient to know only the temperature both temperature and pressure are required to be known both temperature and volume are required to be known both temperature and mass are required to be known

For an ideal gas with constant values of specific heats, for calculation of the specific enthalpy,it is sufficient to know only the temperatureboth temperature and pressu...

Arjun

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Arjun asked Feb 24, 2017

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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...

Arjun

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transfer function for second order system
A second order real system has the following properties.The damping ratio is 0.5 and undamped natural frequency is 10rad/sec, the steady state value at zero is 1.02.the transfer function for the system is?

A second order real system has the following properties.The damping ratio is 0.5 and undamped natural frequency is 10rad/sec, the steady state value at zero is 1.02.the t...

refri_12

140 points

refri_12 asked Feb 16