Question

The high temperature is expected to be near 94^oF. According to what we've learned about thermodynamics, what is the physically correct way to describe the air?

A. the molecules in the air have their rotational and vibrational modes frozen

B. the molecules in the air have a lot of random energy

C. the molecules in the air have a lot of thermal energy

D. the molecules in the air have a lot of random rotational kinetic energy

E. the molecules in the air have a lot of random vibrational kinetic energy

F. the molecules in the air have a lot of random translational kinetic energy

G. the molecules in the air have a lot of heat

Answer 1

F. the molecules in the air have a lot of random translational kinetic energy

Explanation Air is made up of molecules that are constantly in motion. At high temperature near 940 F, the air is sufficiently warmed up and molecules vibrate and collide into each other, increasing the space around each molecule. Because each molecule uses more space for motion, the air expands and becomes less dense (lighter). In other words, the same number of air molecules occupy a larger space. According to thermodynamics, the molecules of air are doing work as they expand. This will affect the air temperature which is the average translational kinetic energy of the molecules in the air