Question

The mass of hydrogen molecule us 3.32 x 10${}^{-27}$ kg.If 10${}^{23}$ hydrogen molecules strike per second at $2c{m}^2$ area of a rigid wall at an angle 45${}^0$ from the normal and rebound back with speed of 1000m/s, then the pressure exerted on the wall is

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

Answer 1

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

Change in momentum for each molecule=$mv\cos {45}^{\circ }-m(-v)\cos {45}^{\circ }=2mnv\cos {45}^{\circ }$

Force exerted=$2mnv\cos {45}^{\circ }n$

where n is number of molecules striking per second

Pressure=$\frac{2mnv\cos {45}^{\circ }}{A}$

$=2.34\times {10}^{3}Pa$