ESS11
Prof. Jin-Yi Yu
The First Law of Thermodynamics
qThis law states that
(1) heat is a form of energy that (2) its conversion
into other forms of energy is such that total
energy is conserved.
qA parcel of air expands
and pushes its surroundings back loses
energy in the process.
q That energy comes from the random motion of the air molecules in the parcel.
q After the expansion, the molecules move less
energetically è the expansion causes the temperature of the air to decrease.