A circular tube with a $3$ cm diameter is connected to a source of flowing water, and water is

passed through the tube at a rate of $100c\frac{m^3}{s}.$ If the pollutant concentration in the water is

constant at $2m\frac{g}{L},$ find: $($a$)$ the mass flux density $($in $m\frac{g}{c}{m}^2-s)$ of the pollutant through the tube

due to advection; $($b$)$ the total mass flux through the tube due to advection.