Question

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.

Answer 1

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

Step-by-step 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

`(v')/(v) = (\rho )/(\rho ')`

`(v')/(v) = (1.18)/(1.05)`

`(v')/(v)` = 1.12

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