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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
An unclothed person whose body has a surface area of 1.40m^2 with emissivity of 0.85 has a skin temperature of 37°C and stands in a 20°C room. How much energy does the person lose per minute?
Ten kilograms of steam at 100°C is condensed is 500 kg of water at 40.0°C. What is the resulting temperature?
How much heat is required to change 10 g of ice at exactly 0°C to steam at 100°C.
Determine the amount of heat required to boil a 20L of water. How much heat is needed to convert it completely into steam.
A steel railroad rail expands and contracts according to the formula Δl = 𝛼lΔT,
where Δl is the change in length, 𝛼 is a constant called the coefficient of linear expansion, l is the original length, and ΔT is the change in temperature. If a 50.0 ft steel rail is installed at 0°F, how many inches will it expand when the temperature rises to 190°F? (𝛼 = 6.5 ✕ 10−6/°F.
What is the speed of sound (in m/s) in carbon dioxide at the normal boiling temperature of water?
