First Law

A thermodynamically closed system contains 1 kg of hydrogen. The system undergoes a reversible polytropic process with polytropic index 1.3. The work output during the process is 400 kJ . During the process, hydrogen beh...

A polytropic process is carried out from an initial pressure of 110 kPa and volume of 5 m 3 to a final volume of 2.5 m 3 . The polytropic index is given by n = 1.2. The absolute value of the work done during the process...

Consider 1 kg of an ideal gas at 1 bar and 300 K contained in a rigid and perfectly insulated container. The specific heat of the gas at constant volume c v is equal to 750 J-kg -1 K -1 . A stirrer performs 225 kJ of wor...

A rigid tank of volume of 8 m 3 is being filled up with air from a pipeline connected through a valve. Initially the valve is closed and the tank is assumed to be completely evacuated. The air pressure and temperature in...

At steady state, 500 kg/s of steam enters a turbine with specific enthalpy equal to 3500 kJ/kg and specific entropy equal to 6.5 kJ-kg -1 K -1 . It expands reversibly in the turbine to the condenser pressure. Heat loss o...

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 $$...

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 $$1100K$$ and $$400K.$$...

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...

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 ___________

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...

Which of the following statements are TRUE with respect to heat and work? $$(i)$$ They are boundary phenomena $$(ii)$$ They are exact differentials $$(iii)$$ They are path functions

A piston-cylinder device initially contains $$0.4\,{m^3}$$ of air (to be treated as an ideal gas) at $$100$$ $$kPa$$ and $${80^ \circ }C.$$ The air is now isothermally compressed to 0.1 m3 . The work done during this pro...

Steam enters a turbine at $$30bar,$$ $${300^ \circ }C$$ $$\left( {u = 2750\,\,kJ/kg,\,\,h = 2993\,\,kJ/kg} \right)$$ and exits the turbine as saturated liquid at $$15$$ $$kPa$$ $$\left( {u = 225\,\,kJ/kg,\,\,h = 226\,\,k...

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

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$...

Work is done on an adiabatic system due to which its velocity changes from $$10$$ $$m/s$$ to $$20$$ $$m/s,$$ elevation increases by $$20$$ $$m$$ and temperature increases by $$1$$ $$K$$. The mass of the system is $$10$$...

$$1.5$$ $$kg$$ of water is in saturated liquid state at $$2$$ bar $$\left( {{v_f} = 0.001061\,\,{m^3}/kg,\,\,{u_f} = 504.0kJ/kg,\,\,{h_f} = 505\,\,kJ/kg} \right).$$ Heat is added in a constant pressure process till the t...

In a power plant, water (density $$ = 1000\,\,kg/{m^3}$$ ) is pumped from $$80$$ $$kPa$$ to $$3$$ $$MPa$$. The pump has an isentropic efficiency of $$0.85.$$ Assuming that the temperature of the water remains the same, t...

A pure substance at $$8$$ $$MPa$$ and $${400^ \circ }C$$ is having a specific internal energy of $$2864$$ $$kJ/kg$$ and a specific volume of $$0.03432\,{m^3}/kg.$$ Its specific enthalpy (in $$kJ/kg$$) is ____________

Steam with specific enthalpy $$\left( h \right)\,\,3214\,\,kJ/kg$$ enters an adiabatic turbine operating at steady state with a flow rate $$10kg/s.$$ As it expands, at a point where $$h$$ is $$2920$$ $$kJ/kg,$$ $$1.5$$ $...

A cylinder contains $$5\,\,{m^3}$$ of an ideal gas at a pressure of $$1$$ bar. This gas is compressed in a reversible isothermal process till its pressure increases to $$5$$ bar. The work in $$kJ$$ required for this proc...

Air enters an adiabatic nozzle at $$300$$ $$kPa,$$ $$500$$ $$K$$ with a velocity of $$10$$ $$m/s.$$ It leaves the nozzle at $$100$$ $$kPa$$ with a velocity of $$180$$ $$m/s.$$ The inlet area is $$80$$ $$c{m^2}.$$ The spe...

Air enters an adiabatic nozzle at $$300$$ $$kPa,$$ $$500$$ $$K$$ with a velocity of $$10$$ $$m/s.$$ It leaves the nozzle at $$100$$ $$kPa$$ with a velocity of $$180$$ $$m/s.$$ The inlet area is $$80$$ $$c{m^2}.$$ The spe...

Steam enters an adiabatic turbine operating at steady state with an enthalpy of $$3251.0kJ/kg$$ and leaves as a saturated mixture at $$15$$ $$kPa$$ with quality (dryness fraction ) $$0.9.$$ The enthalpies of the saturate...

The contents of a well-insulated tank are heated by a resistor of $$23\Omega $$ in which $$10A$$ current is flowing. Consider the tank along with its contents as a thermodynamic system. The work done by the system and th...

A pump handling a liquid raises its pressure from $$1$$ bar to $$30$$ $$bar.$$ Take the density of the liquid as $$990$$ $$kg/{m^3}$$. The isentropic specific work done by the pump in $$kJ/kg$$ is

A mono-atomatic ideal gas $$\left( {\gamma = 1.67,} \right.$$ molecular weight$$=40$$ $$\left. \, \right)$$ is compressed adiabatically from $$0.1$$ $$MPa,$$ $$300K$$ to $$0.2$$ $$MPa.$$ The universal gas constant is $$8...

A frictionless piston-cylinder device contains a gas initially at $$0.8MPa$$ and $$0.015$$ $${m^3}.$$ It expands quasi-statically at constant temperature to a final volume of $$0.030$$ $${m^3}.$$ The work output (in $$kJ...

A compressor undergoes a reversible, steady flow process. The gas at inlet and outlet of the compressor is designated as state $$1$$ and state $$2$$ respectively. Potential and kinetic energy changes are to be ignored. T...

A balloon containing an ideal gas is initially kept in an evacuated and insulated room. The balloon ruptures and the gas fills up the entire room. Which one of the following statements is TRUE at the end of above process...

In a steady state steady flow process taking place in a device with a single inlet and a single outlet, the work done per unit mass flow rate is given by $$W = - \int_{inlet}^{outlet} {vdp} ,$$ where $$v$$ is the specifi...

$$A$$ gas expands in a frictionless piston-cylinder arrangement. The expansion process is very slow, and is resisted by an ambient pressure of $$100kPa.$$ During the expansion process, the pressure of the system (gas) re...

Which of the following relationships is valid only for reversible process undergone by a closed system of simple compressible substance (neglect changes in kinetic and potential energy?

A $$100$$ $$W$$ electric bulb was switched on in a $$2.5\,m \times 3m \times 3m$$ size thermally insulated room having a temperature of $${20^ \circ }C$$. The room temperature at the end of $$24$$ hours will be

A $$100$$ $$W$$ electric bulb was switched on in a $$2.5 \times 3 \times 3m$$ size thermally insulated room having temperature of $${20^0}C.$$ Room temp at the end of $$24$$ hours will be

A football was inflated to a gauge pressure of $$1$$ bar when the ambient temperature was $${15^ \circ }C$$. When the game started next day, the air temperature at the stadium was $${5^ \circ }C$$. Assume that the volume...

A gas contained in a cylinder is compressed, the work required for compression being $$5000$$ $$kJ.$$ During the process, heat interaction of $$200$$ $$kJ$$ causes the surroundings to the heated. The change in internal e...

Nitrogen gas (molecular weight $$28$$) is enclosed in a cylinder by a piston, at the initial condition of $$2$$ bar, $$298$$ $$K$$ and $$1\,\,{m^3}$$. In a particular process, the gas slowly expands under isothermal cond...

A $$2$$ $$kW,$$ $$40$$ liter water heater is switched on for $$20$$ minutes. The heat capacity $${C_p}$$ for water is $$4.2$$ $$kJ/kg$$ $$K.$$ Assuming all the electrical energy has gone into heating the water, increase...

Stream at $$300$$ $$kPa$$ and $${500^ \circ }C\,\,\left( {h = 3486.0\,\,kJ/kg} \right)$$ enters a steam turbine and exits at atmospheric pressure and $${350^ \circ }C\,\,\left( {h = 3175.8\,\,kJ/kg} \right).$$ Heat losse...

A small steam whistle (perfectly insulated and doing no shaft work) causes a drop of $$0.8$$ $$kJ/kg$$ in the enthalpy of steam from entry to exit. If the kinetic energy of the steam at entry is negligible, the velocity...

When an ideal gas with constant specific heats is throttled adiabatically, with negligible changes in kinetic and potential energies

A certain mass of a pure substance undergoes an irreversible process from state $$1$$ to state $$2,$$ the path of the process being a straight line on the $$T$$-$$s$$ diagram. Calculate heat transfer & work done. Some of...

A steam turbine receives steam steadily at $$10$$ $$bar$$ with an enthalpy of $$3000$$ $$kJ/kg$$ and discharges at $$1$$ bar with an enthalpy of $$2700$$ $$kJ/kg.$$ The work output is $$250$$ $$kJ/kg.$$ The changes in ki...

A steel ball of mass $$1$$ $$kg$$ and specific heat $$0.4$$ $$kJ/kg$$ is at temperature of $${60^ \circ }C.$$ It is dropped into $$1$$ $$kg$$ water at $${20^ \circ }C.$$ The final steady state temperature of water is

For reversible adiabatic compression in a steady flow process, the work transfer per unit mass is

A body of weight $$100$$ $$N$$ falls freely a vertical distance of $$50m$$.The atmospheric drag force is $$0.5N.$$ For the body, the work interaction is

The first law of thermodynamics takes the form $$W = - \Delta \,H$$ when applied to :

Which among the following relations is/are valid ONLY for reversible process undergone by a pure substance?

An insulated rigid vessel contains a mixture of fuel and air. The mixture is ignited by a minute spark. The contents of the vessel experience.