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 1.18 kg/m3 at the inlet and 1.05 kg/m3 at the exit, determine the percent increase in the velocity of air as it flows through the hair dryer.

the percent increase in the velocity of air as it flows through the dryer is 12%

Explanation:

given data

density of air ρ  = 1.18 kg/m³

density of air ρ' = 1.05 kg/m³

solution

we know there is only one inlet and exit

so

ρ × A × v = ρ' × A × v'     ........................1

put here value and we get

 = 1.12

so the percent increase in the velocity of air as it flows through the dryer is 12%