Humidity problems and Chapter IV review
Answers are for parents and teachers.
1
At 20 °C φ = 80 % and ρ₀ = 17.3 g/m³. Find the absolute humidity.
ρ = 0.8·17.3 ≈ 13.8 g/m³
2
Air temperature 25 °C (p₀ = 3.17 kPa), dew point 15 °C (p = 1.71 kPa). Estimate φ.
φ = 1.71/3.17·100 % ≈ 54 %
3
A wire has cross-section 2 mm² and a force of 600 N acts on it. What is σ in MPa?
300
4
Why does wet laundry dry in winter frost (after freezing)?
Ice sublimates, i.e. turns into vapour, and the wind carries the vapour away.
5
Water, mercury, alcohol: for which is σ the greatest? (0.073; 0.47; 0.022 N/m)
Mercury (about 0.47 N/m).