A$7-3$ A hair dryer is basically a duct of constant diameter in which a few layers of electric resistors are placed. A small fan pulls the air in and forces it through the resistors where it is heated. If the density of air is $1\mathrm{.}20k\frac{g}{m^3}$ at the inlet and $1\mathrm{.}05k\frac{g}{m^3}$ at the exit, determine the percent increase in the velocity of air as it flows through the hair dryer. Assume steady flow.