# Exam review question on thermodynamics [closed]

A cube has a side length of $20\text{ cm}$. An atom in the gas moves around the cube as shown. It continually bounces off the four lateral walls of the cube. The atom has a mass of $6.6\times 10^{-27}\text{ kg}$. Because of the elastic collisions with the walls, the atom maintains its speed of $300\text{ m/s}$ as it moves around. The figure below shows the view from above looking down into the cube at the path of the atom.

The repeated hits cause there to be a force applied to each of the four lateral faces. Find the force (in Newtons) that it applies to Face 1. Find the force it applies to Face 2.

$$2 \sin(\theta)m v = 2 \sin(60) (6.6\times 10^{-27}) 300\text{ m/s} = 1.2 \times 10^{-24}$$