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)`

Explanation

`{:("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)`