Halliday, Resnick & Walker — The Kinetic Theory of Gases: Problem 15

15 A beam of hydrogen molecules ($H_2$) is directed toward a wall, at an angle of $32^\circ$ with the normal to the wall. Each molecule in the beam has a speed of $1.0 \text{ km/s}$ and a mass of $3.3 \times 10^{-24} \text{ g}$. The beam strikes the wall over an area of $2.0 \text{ cm}^2$, at the rate of $4.0 \times 10^{23} \text{ molecules per second}$. What is the beam’s pressure on the wall?