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A block 4kg in mass rests on a horizontal plane. What value of horizontal force is required to (a) move the block, (b) maintain the motion of the block once it is moved? The coefficients of static and kinetic friction are 0.23 and 0.18, respectively. What will the force be, if the force is instead applied 25° above the horizontal?
The pressure and temperature of mixture of 4 kg of O2 and 6 kg of N2 are 4 bar
and 27°C respectively. For the mixture determine the following ) :i) The mole
fraction of each component ; (ii) The average molecular weight; (iii) The specific
gas constant ; (iv) The volume and density ;(v) The partial pressures and partial
volumes
90 kJ of heat are supplied to a system at a constant volume. The system rejects
95 kJ of heat at constant pressure and 18 kJ of work is done on it. The system
is brought to original state by adiabatic process, i.e. (Heat add or reject of this
process is equal zero). Determine, (i) The adiabatic work; )ii) The values of
internal energy at all end states if initial value is 105 kJ. Draw the
thermodynamic cycle on Pv diagram.
In a vertical frictionless piston and cylinder arrangement, 10 grams of water are
heated to expand from 5 bar and 200oC to 500oC by a heat reservoir at 600oC.
Find work and heat exchanged by water during this process. Find entropy
change of water, heat reservoir and universe.
5. In a turbine, 0.3 kg/s of CO2 expands from 5 bar and 27oC to 1 bar according to
the polytropic process Pv1.2 = constant, in order to produce cold gases for an
industrial process. Find the final temperature as well as heat and mechanical
powers exchanged.
A rigid tank of volume 24 liters contains 0.2 kg of H2O originally at 2 bar. Find
specific volume and initial temperature. What are the phases present (solid,
liquid, vapor?). The tank was heated until its pressure reached 20 bar. Find work
and heat exchanged during this process as well as final temperature
An insulated water heater operating at steady state has two inlets and one
outlet. At inlet 1, liquid water enters at 7 bar, 42oC, and a mass flow rate of 70
kg/s. At inlet 2, wet vapor at 7 bar with a quality of 98% is injected. At outlet,
saturated liquid at 7 bar exits the water heater. Ignoring heat transfer with the
surroundings and neglecting kinetic and potential energy effects, determine
the mass flow rate, in kg/s, at inlet 2
Steam enters with negligible velocity a well-insulated turbine operating at
steady state at 4 MPa, 320°C. The steam expands to an exit pressure of 0.07
MPa, a quality (dryness fraction) of 0.95 and a velocity of 90 m/s. The diameter
of the exit is 0.6 m. Neglecting potential energy effects, find the power
developed by the turbine in kW
Steam is stored in a 0.3m3
rigid tank, initially at 7bar and 440oC. After a long
time, steam temperature was measured and found to be 240oC. Find the final
pressure as well as work and heat exchanged during that time.
In a mixer enters two streams: CO2 at a rate of 2kg/s and 35oC as well as N2 at
a rate of 3 kg/s and 50oC. During mixing, 100kW of heat is added while all inlet
and outlet streams are at 4 bar. Obtain outlet mixture temperature, partial
pressures of each gas.
