Molecular Physics | Thermodynamics Answers

A gas turbine plant receives air at 1 bar and 290°K and compresses it to 5 bar. If the temperature of air after compression is 1000°K; find the thermal efficiency of the turbine

5 mol of an ideal gas at a constant temperature if 0°c. If 2kj of energy is inputted into the system and the net change of internal energy ∆u=0, by what factor does the pressure of the gas change.

A gas is filled with oxygen at a temperature of 25°c to a pressure of 2atm. If the temperature is increased to 50°c and the pressure is increased to 5atm, by what factor does the density of the oxygen increase by.

What happens to the air temperature in valley when cold air blowing from mountain top descending to the valley?

In a transistor, beta=45, the voltage across 5k? resistance which is connected in the collector circuit is 5volts. Find the base current.

A non-insulated pipe passes through a room in which air and walls are at 25°C. The outside

diameter of the pipe is 70 mm, and its surface temperature and emissivity are 200°C and 0.8,

respectively. What are the surface emissive power and irradiation? If the coefficient associated

with free convection heat transfer from the surface is 15W/m2K, what is the rate of heat loss

from the surface per unit length of the pipe?

(E = 2270.48 W/m2

, G = 447.14 W/m2

, Q/l = 997.90 W/m)

4. An automobile tire initially contains 0.25 lbm of air at 30 psig, 70 OF and have an automatic valve

that releases air whenever the pressure exceeds 32 psig. After driving, the temperature of air inside

rises to 120 OF, (a) what mass of air escapes to the atmosphere? lbm, (b) What is the tire gage

pressure when the remaining air inside has returned to 70 OF? psig

3. A steady state, steady flow compressor draws in 236 liters per second of air whose density is

1.268 kgm/m3 and discharges it with a density of 4.88 kgm/m3. At suction P1= 103.39 kPaa; at

discharge, P2 = 551.428 kPaa. The increase of specific internal energy is 78.45 kJ/kgm and the heat

from the air by cooling is 30.17 kJ/kgm. Neglecting the change in potential and kinetic energies,

determine the work in kJ/min.

2. A tank, initially empty, is in the form of a right circular cylinder with hemispherical ends. The overall

length of the cylinder tank is 3 meters and the diameter of the hemisphere is 1 meter. If a pump

discharges a fluid, whose density is 1.2 kgm/Liter, in this tank at a rate of 300 liters per minute

determine a.) Weight of liquid inside the tank after 5 minutes, KN, and b) total time to fill the tank,

min.

1. Saponification is a process wherein soap is added to a certain type of oil to produce grease. One

such grease is said to have 75.7 % by volume oil and 24.3% by volume soap, wherein the oil and

soap have densities 760 kgm/m3 and 6,250 kgm/m3, respectively. This kind of grease is sold by

packs shaped like a sphere with a diameter of 20 cm for convenience. Calculate: a) the mass of

oil per pack (kgm), b) the mass of soap per pack (kgm),c) the weight of each pack (kgf), d) the

specific weight of grease (N/m3), e) will the grease float if it is placed in water whose density is 1000 kgm/m3? Explain