If 10^(20) oxygen molecules per second strike 4cm^2 of wall at an angle of 30^@ with the normal when moving at a speed of 2xx10^3ms^(-1) , find the pressure exerted on the wall . (mass of 1 atom =1.67xx10^(-27)kg)

If 10^(20) oxygen molecules per second strike 4cm^2 of wall at an angl

1.	If 10^(20) oxygen molecules per second strike 4cm^2 of wall at an angle of 30^@ with the normal when moving at a speed of 2xx10^3ms^(-1) , find the pressure exerted on the wall . (mass of 1 atom =1.67xx10^(-27)kg)
Answer» Solution :`{:("Mass of"),("ONE atom"):}} = 1.67xx10^(-27)kg` `{:("Mass of"),("oxygen atom "):}} = 1.67xx10^(-27)xx16` `=26.72xx10^(-27)kg` `{:("Momentum of "),("a molecule P"):}} = mv` Velocity = `2xx10^3ms^(-1)` `P = 26.72xx10^(-7) xx8xx2xx10^3` `=427.5xx10^(-4) kg MS^(-1)` Component of momentum normal to WALL, `P_C=P COS theta` Angle `theta=30^@` `P_C=427.5xx10^(-4)cos30^@` `=427.5xx10^(-4)xxsqrt3/2` `=370.2xx10^(-4)kg ms^(-1)` Pressure `=("Force")/("Area")` `= ("CHANGE in momentum")/("Area")` `=(370xx10^(-4))/(4xx10^(-4))` `=92.55Nm^(-2)` `:.` Pressure `=92.55Nm^(-2)`