How is the position of the air molecules related to the motion of the prongs over time?

Can somebody explain to me how newton's 3rd law relates to momentum? ~ap physics 1

Find v(t), given acceleration a(t)=7j and initial velocity v(0)=k

The freezing and boiling point of a substance changes as the air pressure around it changes. for example, at a lower air pressure (higher altitude) it is easier for water molecules to escape from liquid into the air. in a high altitude city such as denver, colorado compared to a sea-level city such as houston, texas, water