Recent questions in Fluid Mechanics and Thermal Sciences / GO Mechanical

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GATE2018-1-9
For a wo-dimensional incompressible flow field given by $\overrightarrow{u} = A(x \hat{i} - y \hat{j}), \text{ where } A>0$, which one of the following statements is FALSE? It satisfies continuity equation It is unidirectional when $x \rightarrow 0$ and $y \rightarrow \infty$ Its streamlines are given by $x=y$ It is irrotational

For a wo-dimensional incompressible flow field given by $\overrightarrow{u} = A(x \hat{i} - y \hat{j}), \text{ where } A>0$, which one of the following statements is FALS...

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Arjun asked Feb 17, 2018

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GATE2017 ME-2: 45
The volume and temperature of air (assumed to be an ideal gas) in a closed vessel is $2.87 m^{3}$ and $300 \: K$, respectively. The gauge pressure indicated by a manometer fitted to the wall of the vessel is $0.5$ bar. If the gas constant of air is $R=287 \: J/kg.K$ and the atmospheric pressure is $1$ bar, the mass of air (in $kg$) in the vessel is $1.67$ $3.33$ $5.00$ $6.66$

The volume and temperature of air (assumed to be an ideal gas) in a closed vessel is $2.87 m^{3}$ and $300 \: K$, respectively. The gauge pressure indicated by a manomete...

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Arjun asked Feb 26, 2017

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GATE2017 ME-2: 46
In a counter-flow heat exchanger, water is heated at the rate of $1.5 \: kg/s$ from $40^{\circ}$ C to $80^{\circ} \: C$ by an oil entering at $120^{\circ}$ C and leaving at $60 ^{\circ}$ C. The specific heats of water and oil are $4.2 \: kJ/kg.K$ and ... transfer coefficient is $400 W/m^{2}.K$. The required heat transfer surface area (in $m^{2}$) is $0.104$ $0.022$ $10.4$ $21.84$

In a counter-flow heat exchanger, water is heated at the rate of $1.5 \: kg/s$ from $40^{\circ}$ C to $80^{\circ} \: C$ by an oil entering at $120^{\circ}$ C and leaving ...

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GATE2017 ME-2: 47
A metal ball of diameter $60$ mm is initially at $220^{\circ}$ C. The ball is suddenly cooled by an air jet of $20^{\circ}$ C. The heat transfer coefficient is $200 W/m^{2}.K$ ... $^{\circ} C$) after $90$ seconds will be approximately $141$ $163$ $189$ $210$

A metal ball of diameter $60$ mm is initially at $220^{\circ}$ C. The ball is suddenly cooled by an air jet of $20^{\circ}$ C. The heat transfer coefficient is $200 W/m^{...

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GATE2017 ME-2: 44
One kg of an ideal gas (gas constant $R= 287\: J/kg.K$) undergoes an irreversible process from state-$1$ ($1$ bar, $300 \: K$) to state-$2$ ($2$ bar, $300\: K$). The change in specific entropy $(s_{2} - s_{1})$ of the gas (in $J/kg.K$) in the process is _________.

One kg of an ideal gas (gas constant $R= 287\: J/kg.K$) undergoes an irreversible process from state-$1$ ($1$ bar, $300 \: K$) to state-$2$ ($2$ bar, $300\: K$). The chan...

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GATE2017 ME-2: 43
A calorically perfect gas (specific heat at constant pressure $1000 \: J/kg .K$) enters and leaves a gas turbine with the same velocity. The temperatures of the gas at turbine entry and exit are $1100 \: K $and $400 \: K$, respectively. The power produced is $4.6\: MW$ ... turbine casing. The mass flow rate of the gas (in $kg/s$) through the turbine is $6.14$ $7.00$ $7.50$ $8.00$

A calorically perfect gas (specific heat at constant pressure $1000 \: J/kg .K$) enters and leaves a gas turbine with the same velocity. The temperatures of the gas at tu...

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GATE2017 ME-2: 42
In the Rankine cycle for a steam power plant, the turbine entry and exit enthalpies are $2803 \: kJ/kg$ and $1800 \: kJ/kg$, respectively. The enthalpies of water at pump entry and exit are $121 \: kJ/kg$ and $124 \: kJ/kg$, respectively. The specific steam consumption (in $kg/kW.h$) of the cycle is _________.

In the Rankine cycle for a steam power plant, the turbine entry and exit enthalpies are $2803 \: kJ/kg$ and $1800 \: kJ/kg$, respectively. The enthalpies of water at pump...

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GATE2017 ME-2: 41
For the laminar flow of water over a sphere, the drag coefficient $C_{F}$ is defined as $C_{F}=F/(\rho U^{2} D^{2})$, where $F$ is the drag force, $\rho$ is the fluid density, $U$ is the fluid velocity and $D$ is the diameter ... $200$ mm under dynamically similar conditions, the drag force (in N) on this sphere is ________.

For the laminar flow of water over a sphere, the drag coefficient $C_{F}$ is defined as $C_{F}=F/(\rho U^{2} D^{2})$, where $F$ is the drag force, $\rho$ is the fluid den...

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GATE2017 ME-2: 40
A $60$ mm-diameter water jet strikes a plate containing a hole of $40$ mm diameter as shown in the figure. Part of the jet passes through the hole horizontally and the remaining is deflected vertically. The density of water is $1000 kg/m^{3}$. If velocities are as indicated in the figure, the magnitude of horizontal force (in N) required to hold the plate is _________.

A $60$ mm-diameter water jet strikes a plate containing a hole of $40$ mm diameter as shown in the figure. Part of the jet passes through the hole horizontally and the re...

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GATE2017 ME-2: 39
The arrangement shown in the figure measures the velocity $V$ of a gas of density $1 kg/m^{3}$ flowing through a pipe. The acceleration due to gravity is $9.81 m/s^{2}$. If the manometric fluid is water (density $1000 \: kg/m^{3}$) and the velocity $V$ is $20 m/s$, the differential head $h$ (in mm) between the two arms of the manometer is __________.

The arrangement shown in the figure measures the velocity $V$ of a gas of density $1 kg/m^{3}$ flowing through a pipe. The acceleration due to gravity is $9.81 m/s^{2}$. ...

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GATE2017 ME-2: 19
The emissive power of a blackbody is $P$. If its absolute temperature is doubled, the emissive power becomes $2 P$ $4 P$ $8 P$ $16 P$

The emissive power of a blackbody is $P$. If its absolute temperature is doubled, the emissive power becomes$2 P$$4 P$$8 P$$16 P$

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GATE2017 ME-2: 18
The heat loss from a fin is $6$ W. The effectiveness and efficiency of the fin are $3$ and $0.75$, respectively. The heat loss (in W) from the fin, keeping the entire fin surface at base temperature, is _______.

The heat loss from a fin is $6$ W. The effectiveness and efficiency of the fin are $3$ and $0.75$, respectively. The heat loss (in W) from the fin, keeping the entire fin...

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GATE2017 ME-2: 17
Consider a laminar flow at zero incidence over a flat plate. The shear stress at the wall is denoted by $\tau _{w}$. The axial positions $x_{1}$ and $x_{2}$ on the plate are measured from the leading edge in the direction of flow. If $x_{2} > x_{1}$ ... $\tau _{w}\mid _{x_{1}} < \tau _{w}\mid _{x_{2}}$

Consider a laminar flow at zero incidence over a flat plate. The shear stress at the wall is denoted by $\tau _{w}$. The axial positions $x_{1}$ and $x_{2}$ on the plate ...

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GATE2017 ME-2: 16
For the stability of a floating body the Centre of buoyancy must coincide with the centre of gravity. Centre of buoyancy must be above the centre of gravity. Centre of gravity must be above the centre of buoyancy. Metacentre must be above the centre of gravity.

For the stability of a floating body theCentre of buoyancy must coincide with the centre of gravity.Centre of buoyancy must be above the centre of gravity.Centre of gravi...

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GATE2017 ME-2: 15
If a mass of moist air contained in a closed metallic vessel is heated, then its Relative humidity decreases. Relative humidity increases. Specific humidity increases. Specific humidity decreases.

If a mass of moist air contained in a closed metallic vessel is heated, then its Relative humidity decreases.Relative humidity increases.Specific humidity increases.Speci...

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GATE2017 ME-2: 14
A mass $m$ of a perfect gas at pressure $p_{1}$ and volume $V_{1}$ undergoes an isothermal process. The final pressure is $p_{2}$ and volume is $V_{2}$. The work done on the system is considered positive. If $R$ is the gas constant and $T$ is the temperature, then the work done in the ... $RT \ln \dfrac{V_{2}}{V_{1}} \\$ $-mRT \ln \dfrac{P_{2}}{P_{1}}$

A mass $m$ of a perfect gas at pressure $p_{1}$ and volume $V_{1}$ undergoes an isothermal process. The final pressure is $p_{2}$ and volume is $V_{2}$. The work done on ...

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GATE2017 ME-2: 13
Which one of the following statements is TRUE? Both Pelton and Francis turbines are impulse turbines. Francis turbine is a reaction turbine but Kaplan turbine is an impulse turbine. Francis turbine is an axial-flow reaction turbine. Kaplan turbine is an axial-flow reaction turbine.

Which one of the following statements is TRUE?Both Pelton and Francis turbines are impulse turbines.Francis turbine is a reaction turbine but Kaplan turbine is an impulse...

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GATE2017 ME-2: 10
A steel bar is held by two fixed supports as shown in the figure and is subjected to an increase of temperature $\Delta T=100^{\circ}C$. If the coefficient of thermal expansion and Young's modulus of elasticity of steel are $11 \times 10^{-6}/^{\circ} C$ and $200$ GPa, respectively, the magnitude of thermal stress (in MPa) induced in the bar is _______

A steel bar is held by two fixed supports as shown in the figure and is subjected to an increase of temperature $\Delta T=100^{\circ}C$. If the coefficient of thermal exp...

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GATE2017 ME-1: 38
Heat is generated uniformly in a long solid cylindrical rod (diameter$=10$ mm) at the rate of $4 \times 10^{7} W/m^{3}$. The thermal conductivity of the rod material is $25 W/m.K$. Under steady state conditions, the temperature difference between the centre and the surface of the rod is ______ $^{\circ} C$.

Heat is generated uniformly in a long solid cylindrical rod (diameter$=10$ mm) at the rate of $4 \times 10^{7} W/m^{3}$. The thermal conductivity of the rod material is $...

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GATE2017 ME-1: 37
Two black surfaces, AB and BC, of lengths $5$ m and $6$ m, respectively, are oriented as shown. Both surfaces extend infinitely into the third dimension. Given that view factor $F_{12}=0.5, T_{1}=800 K, T_{2}=600 K, T_{\text{surrounding}}=300 K$ and Stefan- ... $2$ to the surrounding environment is _______ kW.

Two black surfaces, AB and BC, of lengths $5$ m and $6$ m, respectively, are oriented as shown. Both surfaces extend infinitely into the third dimension. Given that view ...

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GATE2017 ME-1: 36
Air contains $79\%$ $N_{2}$ and $21\%$ $O_{2}$ on a molar basis. Methane $(CH_{4})$ is burned with $50\%$ excess air than required stoichiometrically. Assuming complete combustion of methane, the molar percentage of $N_{2}$ in the products is _______.

Air contains $79\%$ $N_{2}$ and $21\%$ $O_{2}$ on a molar basis. Methane $(CH_{4})$ is burned with $50\%$ excess air than required stoichiometrically. Assuming complete c...

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GATE2017 ME-1: 35
Moist air is treated as an ideal gas mixture of water vapour and dry air (molecular weight of air$= 28.84$ and molecular weight of water $=18$). At a location, the total pressure is $100$ kPa, the temperature is $30^{\circ}$ C and the relative humidity is ... saturation pressure of water at $30^{\circ} C$ is $4246$ Pa, the mass of water vapour per kg of dry air is _________ grams.

Moist air is treated as an ideal gas mixture of water vapour and dry air (molecular weight of air$= 28.84$ and molecular weight of water $=18$). At a location, the total ...

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Arjun asked Feb 26, 2017

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GATE2017 ME-1: 33
One kg of an ideal gas (gas constant, $R= 400 J/kg.K$; specific heat at constant volume, $c_{v}=1000 J/kg.K$) at $1$ bar, and $300$ K is contained in a sealed rigid cylinder. During an adiabatic process, $100$ kJ of work is done on the system by a stirrer. The increase in entropy of the system is _______ $J/K$.

One kg of an ideal gas (gas constant, $R= 400 J/kg.K$; specific heat at constant volume, $c_{v}=1000 J/kg.K$) at $1$ bar, and $300$ K is contained in a sealed rigid cylin...

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GATE2017 ME-1: 30
The velocity profile inside the boundary layer for flow over a flat plate is given as $\dfrac{u}{U_{\infty }}= \sin \left ( \dfrac{\Pi }{2}\dfrac{y}{\delta } \right )$, where $U_{\infty}$ is the free stream velocity and $\delta$ is the local boundary layer thickness. If $\delta^{*}$ is ... $\dfrac{2}{\Pi } \\$ $1-\dfrac{2}{\Pi } \\$ $1+\dfrac{2}{\Pi } \\$ $0$

The velocity profile inside the boundary layer for flow over a flat plate is given as $\dfrac{u}{U_{\infty }}= \sin \left ( \dfrac{\Pi }{2}\dfrac{y}{\delta } \right )$, w...

Arjun

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GATE2017 ME-1: 31
Consider steady flow of an incompressible fluid through two long and straight pipes of diameters $d_{1}$ and $d_{2}$ arranged in series. Both pipes are of equal length and the flow is turbulent in both pipes. The friction factor for turbulent flow though pipes is of the form, $f=K(Re)^{-n}$, where ... $\left ( \dfrac{d_{2}}{d_{1}} \right )^{(5+n)}$

Consider steady flow of an incompressible fluid through two long and straight pipes of diameters $d_{1}$ and $d_{2}$ arranged in series. Both pipes are of equal length an...

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GATE2017 ME-1: 32
For a steady flow, the velocity field is $\vec{V}=(-x^{2}+3y)\hat{i}+(2xy)\hat{j}$. The magnitude of the acceleration of a particle at $(1, -1)$ is $2$ $1$ $2\sqrt{5}$ $0$

For a steady flow, the velocity field is $\vec{V}=(-x^{2}+3y)\hat{i}+(2xy)\hat{j}$. The magnitude of the acceleration of a particle at $(1, -1)$ is$2$$1$$2\sqrt{5}$$0$

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GATE2017 ME-1: 34
The pressure ratio across a gas turbine (for air, specific heat at constant pressure, $c_{p}=1040 J/kg.K$ and ratio of specific heats, $\gamma=1.4$) is $10$. If the inlet temperature to the turbine is $1200$ K and the isentropic efficiency is $0.9$, the gas temperature at turbine exit is ________ $K$

The pressure ratio across a gas turbine (for air, specific heat at constant pressure, $c_{p}=1040 J/kg.K$ and ratio of specific heats, $\gamma=1.4$) is $10$. If the inlet...

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GATE2017 ME-1: 12
A heat pump absorbs $10$kW of heat from outside environment at $250$ K while absorbing $15$ kW of work. It delivers the heat to a room that must be kept warm at $300$ K. The Coefficient of Performance (COP) of the heat pump is ________.

A heat pump absorbs $10$kW of heat from outside environment at $250$ K while absorbing $15$ kW of work. It delivers the heat to a room that must be kept warm at $300$ K. ...

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GATE2017 ME-1: 11
The molar specific heat at constant volume of an ideal gas is equal to $2.5$ times the universal gas constant ($8.314$ J/mol.K). When the temperature increases by $100$K, the change in molar specific enthalpy is __________ J/mol.

The molar specific heat at constant volume of an ideal gas is equal to $2.5$ times the universal gas constant ($8.314$ J/mol.K). When the temperature increases by $100$K,...

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GATE2017 ME-1: 7
Consider the two-dimensional velocity field given by $\overrightarrow{V}=(5+a_{1}x+b_{1}y)\hat{i}+(4+a_{2}x+b_{2}y)\hat{j}$, where $a_{1}, b_{1}, a_{2}$ and $b_{2}$ are constants. Which one of the following conditions needs to be satisfied for the flow to be incompressible? $a_{1}+b_{1}=0$ $a_{1}+b_{2}=0$ $a_{2}+b_{2}=0$ $a_{2}+b_{1}=0$

Consider the two-dimensional velocity field given by $\overrightarrow{V}=(5+a_{1}x+b_{1}y)\hat{i}+(4+a_{2}x+b_{2}y)\hat{j}$, where $a_{1}, b_{1}, a_{2}$ and $b_{2}$ are c...

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GATE2017 ME-1: 6
For steady flow of a viscous incompressible fluid through a circular pipe of constant diameter, the average velocity in the fully developed region is constant. Which one of the following statements about the average velocity in the developing region is TRUE? ... the flow is fully developed. It is constant but is always lower than the average velocity in the fully developed region.

For steady flow of a viscous incompressible fluid through a circular pipe of constant diameter, the average velocity in the fully developed region is constant. Which one ...

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GATE2017 ME-1: 8
Water (density $= 1000 kg/m^{3}$) at ambient temperature flows through a horizontal pipe of uniform cross section at the rate of $1 kg/s$. If the pressure drop across the pipe is $100$ KPa, the minimum power required to pump the water across the pipe, in watts, is ______.

Water (density $= 1000 kg/m^{3}$) at ambient temperature flows through a horizontal pipe of uniform cross section at the rate of $1 kg/s$. If the pressure drop across the...

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GATE2017 ME-1: 9
Which one of the following is NOT a rotating machine? Centrifugal pump Gear pump Jet pump Vane pump

Which one of the following is NOT a rotating machine?Centrifugal pumpGear pumpJet pumpVane pump

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GATE2017 ME-1: 10
Saturated steam at $100^{\circ} C$ condenses on the outside of a tube. Cold fluid enters the tube at $20^{\circ} C$ and exits at $50^{\circ} C$. The value of the Log mean Temperature Difference (LMTD) is ________ $^{\circ}$ C.

Saturated steam at $100^{\circ} C$ condenses on the outside of a tube. Cold fluid enters the tube at $20^{\circ} C$ and exits at $50^{\circ} C$. The value of the Log mean...

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GATE2016-3-44
Steam at an initial enthalpy of $100$ $kJ/kg$ and inlet velocity of $100$ $m/s$, enters an insulated horizontal nozzle. It leaves the nozzle at $200$ $m/s$. The exit enthalpy (in $kJ/kg$) is __________

Steam at an initial enthalpy of $100$ $kJ/kg$ and inlet velocity of $100$ $m/s$, enters an insulated horizontal nozzle. It leaves the nozzle at $200$ $m/s$. The exit enth...

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Arjun asked Feb 24, 2017

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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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Arjun asked Feb 24, 2017

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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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Arjun asked Feb 24, 2017

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GATE2016-3-47
In the vapour compression cycle shown in the figure, the evaporating and condensing temperatures are $260 \: K$ and $310 \: K$, respectively. The compressor takes in liquid-vapour mixture (state $1$) and isentropically compresses it to a dry saturated vapour condition (state ... $1$ and $0$ (in $kJ/kg$) is ____________

In the vapour compression cycle shown in the figure, the evaporating and condensing temperatures are $260 \: K$ and $310 \: K$, respectively. The compressor takes in liqu...

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GATE2016-3-52
Two optically flat plates of glass are kept at a small angle $\theta$ as shown in the figure. Monochromatic light is incident vertically. If the wavelength of light used to get a fringe spacing of $1$ $mm$ is $450$ $nm$, the wavelength of light (in $nm$) to get a fringe spacing of $1.5$ $mm$ is _________

Two optically flat plates of glass are kept at a small angle $\theta$ as shown in the figure. Monochromatic light is incident vertically.If the wavelength of light used t...

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GATE2016-3-41
For a two-dimensional flow, the velocity field is $\overrightarrow{u}=\dfrac{x}{x^2+y^2}\hat{i}+\dfrac{y}{x^2+y^2}\hat{j}$ where$\hat{i}$ and $\hat{j}$ are the basis vectors in the $x-y$ Cartesian coordinate system. Identify the CORRECT statements from below. The flow is incompressible. The flow is ... $(2)$ and $(3)$ $(1)$ and $(3)$ $(1)$ and $(2)$ $(3)$ and $(4)$

For a two-dimensional flow, the velocity field is $\overrightarrow{u}=\dfrac{x}{x^2+y^2}\hat{i}+\dfrac{y}{x^2+y^2}\hat{j}$ where$\hat{i}$ and $\hat{j}$ are the basis vec...

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Arjun asked Feb 24, 2017