Building Services Engineering 5th Edition Handbook

400 Understanding units
15. Which is correct about the density of water?
1. Cannot be measured.
2. Cannot be measured accurately.
3. Always relative to the specific gravity number.
4. 1000 times that of air.
5. Specific gravity is 1.0.
16. Which is correct about the density of water?
1. 1.205 × 10 5 kg/m 3 .
2. 1 tonne/m 3 at 4 ◦ C.
3. 1.012 × 10 3 kJ/m 3 .
4. 1.27 kJ/kg K.
5. 100 g/cm 3 .
17. Which is correct about the density of water?
1. 1 g/cm 3 .
2. 1.2 × 10 3 kg/m 3 .
3. Specific gravity is 4.186.
4. 1000 tonne/m 3 at 10 ◦ C.
5. 1 kg/l.
18. What does the exponential e mean?
1. A logarithm.
2. A variable number.
3. Always 10 x , ten to the power x.
4. 2.718.
5. Has no meaning.
19. What does the exponential e mean?
1. Something which is raised to a power.
2. e = 10 x .
3. The sum of an infinite series.
4. e = √ −1.
5. e 1 = 2.718.
20. Which of these has the correct units?
1. Mass is measured in kilograms.
2. 1 tonne = 10 6 kg.
3. 1 kg = 10 9 mg.
4. 10 3 kg/m 3 = 1 kg/l.
5. 10 6 m = 1 km.
21. Which of these are not the correct units?
1. 1 h = 3600 s.
2. 60 h = 3600 min.
3. 3.6 × 10 3 s = 1h.
4. 1 year = 8760 h.
5. 1 h = 360 s.