An expressway was initially operating under condition $A(q=700ve\frac{h}{h},k=10ve\frac{h}{k}m).$ At time $2$:$30$ pm a slow truck enters the expressway travelling at speed of $13\mathrm{.}3k\frac{m}{h}.$ The truck has taken an exit which is $6\mathrm{.}67km$ away from the entry point. Other important points are condition B $(q=1600ve\frac{h}{h}k=120ve\frac{h}{k}m)$ before the truck leaves the system, and condition C $(q=2200ve\frac{h}{h}k=60ve\frac{h}{k}m)$ after the truck leaves the system. The free$-$flow speed is $75k\frac{m}{h}0(q=0ve\frac{h}{h}k=6$ veh $\frac{?}{km}).$ Identify the disappear.

$(6)$

While explaining the mesoscopic traffic models, describe the gas$-$kinetic theory models.