The total number of particles that reach area d A within time interval d t also depends on the velocity distribution; All in all, it calculates to be: n v cos ⁡ ⁡ ( θ θ ) d A d t × × ( m 2 π π k B T ) 3 / 2 e − − m v 2 2 k B T ( v 2 sin ⁡ ⁡ ( θ θ ) d v d θ θ d ϕ ϕ ) .