Higher Future Institute of Engineering and Technology
First year mechanical engineering
Chapter 1: Basic Concepts of Thermodynamics
SHEET 1
Mass, Force, and Units
1–7C What is the net force acting on a car cruising at a constant velocity of 70
km/h (a) on a level road and (b) on an uphill road?
1–9 What is the weight, in N, of an object with a mass of 200 kg at a location
where g = 9.6 𝑚/𝑠 2?
1–10 A 3-kg plastic tank that has a volume of 0.2 𝑚3 is filled with liquid water.
Assuming the density of water is 𝜌 = 1000 𝑘g/𝑚3, determine the weight of the
combined system.
Temperature:
1–35E What is the temperature of the heated air at 150𝑜 C in °F and R?
1–38E The temperature of ambient air in a certain location is measured to be
−40 °C. Express this temperature in Fahrenheit (°F), Kelvin (K), and Rankine
(R) units.
1–39E The temperature of a system drops by 45𝑜 F during a cooling process.
Express this drop in temperature in K, R, and °C.
Pressure, Manometer, and Barometer:
1–45 A vacuum gage connected to a chamber reads 35 kPa at a location where
the atmospheric pressure is 92 kPa.
Determine: the absolute pressure in the chamber.
1–46 The pressure in a compressed air storage tank is 1200 kPa. What is the
tank’s pressure in:
(a) kN and m units; (b) kg, m, and s units; and (c) kg, km, and s units?
1
Higher Future Institute of Engineering and Technology
First year mechanical engineering
1–48E If the pressure inside a rubber balloon is 1500 mmHg, what is this
pressure in pounds-force per square inch (psi)?
1–64 Both a gage and a manometer are attached to a gas tank
to measure its pressure. If the reading on the pressure gage is
80 kPa, determine the distance between the two fluid levels of
the manometer if the fluid is (a) mercury (𝜌 = 13600𝑘g/𝑚3)
or (b) water (𝜌 = 1000 𝑘g/𝑚 3).
1–66 A manometer containing oil (𝜌 = 850 𝑘g/𝑚 3) is
attached to a tank filled with air. If the oil-level difference between the two
columns is 80 cm and the atmospheric pressure is 98 kPa, determine the absolute
pressure of the air in the tank.
1–73 Determine the pressure exerted on a diver at 45 m below the free surface of
the sea. Assume a barometric pressure of 101 kPa and a specific gravity of 1.03
for seawater.
1–75 Consider a double-fluid manometer attached to an air
pipe shown in Fig. If the specific gravity of one fluid is
13.55, determine the specific gravity of the other fluid for the
indicated absolute pressure of air. Take the atmospheric
pressure to be 100 kPa.
1–120 Consider a fish swimming 5 m below the free surface of water. The
increase in the pressure exerted on the fish when it dives to a depth of 25 m
below the free surface is:
(a) 196 Pa (b) 5400 Pa (c) 30,000 Pa (d ) 196,000 Pa (e) 294,000 Pa
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Higher Future Institute of Engineering and Technology
First year mechanical engineering
1–121 The atmospheric pressures at the top and the bottom of a building are read
by a barometer to be 96.0 and 98.0 kPa.
If the density of air is 1.0 kg/m3, the height of the building is:
(a) 17 m (b) 20 m (c) 170 m (d ) 204 m (e) 252 m
1–122 Consider a 2-m deep swimming pool. The pressure difference between the
top and bottom of the pool is:
(a) 12.0 kPa (b) 19.6 kPa (c) 38.1 kPa (d ) 50.8 kPa (e) 200 kPa
1–123 During a heating process, the temperature of an object rises by 10°C. This
temperature rise is equivalent to a temperature rise of:
(a) 10°F (b) 42°F (c) 18 K (d ) 18 R (e) 283 K
1–124 At sea level, the weight of 1 kg mass in SI units is 9.81 N. The weight of
1 lbm mass in English units is:
(a) 1 lbf (b) 9.81 lbf (c) 32.2 lbf (d ) 0.1 lbf (e) 0.031 lbf
