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

Answer:

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

$\frac{v'}{v} = \frac{\rho }{\rho '}$  

$\frac{v'}{v} = \frac{1.18}{1.05}$  

$\frac{v'}{v}$  = 1.12

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