Answer to Question #279508 in Classical Mechanics for Kyutii

Question

In an unhealthy, dusty cement mill, there was 2.6x10

9 dust particles (sp g =3.0) per

cubic meter of air. Assuming the particles to be spheres of 2.0 µm diameter, calculate

the mass of dust (a) in a 20mx15mx80m room and (b) inhaled in each average

breath of 400-cm3 volume

Answer 1

$m=N\rho V_0,$

$N=nV,$

$V_0=\frac{\pi d^3}6,$

$m=\frac{n\rho\pi d^3}6 V,$

a)

$m=784~g,$

b)

$m=13~ng.$