Question

Consider a gas inside a box. It exerts some pressure on its walls. Find this value. GIven that number of molecules per unit volume be 20, mass of each molecule 10^-20kg, vx^2 = 1m^2/s^2.

(a) 20*10^-20Pa

(b) 20/3*10^-20Pa

(c) 20/3*10^-19Pa

(d) 20*10^-19Pa

I have been asked this question in examination.

My question comes from Kinetic Theory of an Ideal Gas in portion Kinetic Theory of Physics – Class 11

Answer 1

Right option is (a) 20*10^-20Pa

To explain I would say: Pressure is given by (1/3)nmv^2.

v^2 = 3vx^2 = 3m^2/s^2.

P = (1/3)*20*10^-20*3

= 20*10^-20Pa.