Atmospheric Physics : Phase Changes (Use phase diagram physics and some cases in

Question

Atmospheric Physics : Phase Changes (Use phase diagram physics and some cases include energy input/output and the right terminology)

a) Why will the water in a birdbath eventually evaporate, instead of establishing the equilibrium vapor pressure?
b) Onions contain this compound [(Z)-propanethial S-oxide] which makes you cry. Apparently you can reduce the crying buy refrigerating onions before cutting. Why?

c) Why does blowing on hot soup cool it off? why does "whistling backwards" cool your mouth (hint: it is not just contact with cold air) .

Explanation / Answer

a) Water in birdbath will eventually evaporate because the Cp of atmospehere is infinite, meaning thet the atmosphere can absorb infinite heat before coming to a thermal equilibrium with the surroudsings.
b) The rate of evaporation is directly proportional to absolte temperature, so freezing reduces rate of evaporation of the gas that causes tears, and hebce reduces watery eyes.

c) Blowing hot soup removes the air at higher temperature around it, hence by newton's law, help[s in better coooling. Whistling backwards pulls air to mouth, so reducing temperature of mouth a to newton's cooling

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.