Question

The mass of a hydrogen molecule is $3.32\times {10}^{-27}kg$. If ${10}^{23}$ hydrogen molecules strike per second on a fixed wall of area $2{cm}^2$ at an angle of ${45}^{\circ }$ to the normal, and rebound elastically with a speed of ${10}^3$ $m/s$, then the pressure on the wall is nearly

• A. $2.35\times {10}^2\frac{N}{m^2}$
  
• B. $4.70\times {10}^2\frac{N}{m^2}$
  
• C. $2.35\times {10}^{3}N/m^2$
• D. $4.70\times {10}^3\frac{N}{m^2}$
  

Answer 1

The correct option is C $2.35\times {10}^{3}N/m^2$


$F_{ovg}=2NmV\cos \theta$

Pressure = $\frac{2NmV}{A}$
$=\frac{2\left({10}^{23}\right)(3.32\times {10}^{-27})\frac{1}{\sqrt{2}}\times {10}^3}{2\times {10}^{-4}}$
$=2.35\times {10}^{3}N/m^2$