Identify which of the following are extensive properties and which are intensive properties:
(a) a 10-m3 volume,
(b) 30 J of kinetic energy,
(c) a pressure of 90 kPa,
(d) a stress of 1000 kPa,
(e) a mass of 75 kg, and
(f) a velocity of 60 m/s.
Convert all extensive properties to intensive properties assuming m = 75 kg.
(a) Extensive - Volume
(b) Intensive - Kinetic energy
(c) Intensive - Pressure
(d) Intensive - Stress
(e) Extensive - Mass
(f) Intensive - Velocity
To convert extensive properties to intensive properties assuming m = 75 kg, we divide the extensive properties by the mass:
(a) 10 m^3 / 75 kg = 0.1333 m^3/kg
(e) 75 kg / 75 kg = 1
The converted extensive property (a) becomes an intensive property of 0.1333 m^3/kg.
Extensive properties are dependent on the amount of substance present, while intensive properties are independent of the amount of substance present.
(a) Volume (10 m^3) is an extensive property because it depends on the amount of substance present.
(b) Kinetic energy (30 J) is also an extensive property because it depends on the amount of substance present.
(c) Pressure (90 kPa) is an intensive property because it does not depend on the amount of substance present.
(d) Stress (1000 kPa) is an intensive property because it does not depend on the amount of substance present.
(e) Mass (75 kg) is an extensive property because it depends on the amount of substance present.
(f) Velocity (60 m/s) is an intensive property because it does not depend on the amount of substance present.
To convert extensive properties to intensive properties, we need to divide them by the mass (m).
(a) Volume (10 m^3) / Mass (75 kg) = 0.133 m^3/kg
(b) Kinetic energy (30 J) / Mass (75 kg) = 0.4 J/kg
(e) Mass (75 kg) / Mass (75 kg) = 1 (no conversion needed)
So, the converted values for (a), (b), and (e) are 0.133 m^3/kg, 0.4 J/kg, and 1, respectively.