Fundamentals of Physics

What crushed the tank car during the night?

The interior of this railroad tank car was being cleaned with steam by a crew late one afternoon. Because the job was unfinished at the end of their work shift, they sealed the car and left for the night. When they returned the next morning, they discovered that something had crushed the car in spite of its extremely strong steel walls, as if some giant creature from a grade B science fiction movie had stepped on it during a rampage that night.

The answer is in this chapter.

19-1  What Is Physics?

One of the main subjects in thermodynamics is the physics of gases. A gas consists of atoms (either individually or bound together as molecules) that fill their container’s volume and exert pressure on the container’s walls. We can usually assign a temperature to such a contained gas. These three variables associated with a gas—volume, pressure, and temperature—are all a consequence of the motion of the atoms. The volume is a result of the freedom the atoms have to spread throughout the container, the pressure is a result of the collisions of the atoms with the container’s walls, and the temperature has to do with the kinetic energy of the atoms. The kinetic theory of gases, the focus of this chapter, relates the motion of the atoms to the volume, ...