Question

The mass of hydrogen molecules is $3.32\times {10}^{-27}kg$. If ${10}^{23}$ hydrogen molecules strike per second at $2c{m}^2$ area of a rigid wall at an angle of ${45}^o$ from the normal and are rebound back with speed of $1000m/s$, then the pressure exerted on the wall is

• A. $23.4\times {10}^{3}Pascal$
• B. $2.34\times {10}^{3}Pascal$
• C. $0.23\times {10}^{3}Pascal$
• D. $2Pascal$

Answer 1

The correct option is B $2.34\times {10}^{3}Pascal$

Pressure will be due to the normal force exerted on the wall the Normal force on the wall per molecule $=2mvcos\left(45\right)$

Total normal force on the wall $=nmvcos\left(45\right)$

$=2\times {10}^{23}\times 3.32\times {10}^{-27}\times 1000\times cos\left(45\right)$

$=2\times 2347.9\times 10{}^{-}4$

Pressure on the wall $=F/area$

$=2\times 2347.9\times {10}^{-4}/2\times {10}^{-}4$

$=\mathrm{2.2347.9}$$=2.34\times {10}^3$ pascal