Question

Atmospheric pressure is measured to be 14.769 psia. a. What would be the equivalent reading of a water barometer (inches of H20)? b. What would be the equivalent reading of a Mercury barometer (mm of Hg)?

Answer 1

Answer:

(a) water height =408.66 in.

(b) mercury height=30.04 in.

Explanation:

Given: P=14.769 psi     ( 1 psi= 6894.76 $\frac{N}{m^2}$ )

we know that   $P=\rho\times g\timesh$

where $\rho =Density,g=9.81\frac{m}{s^2}$

     h=height.

Given that P=14.769 psi ⇒P= 101828.6 7$\dfrac{N}{m^2}$

(a) $P=\rho_{w}\times g\times h_{w}$  

     $\rho_{w}=1000\frac{Kg}{m^3}$

⇒101828.67=$1000\times 9.81\times h_{w}$

$h_{w}$=10.38 m

So water barometer will read 408.66 in.            (1 m=39.37 in)

(b)  $P=\rho_{hg}\times g\times h_{hg}$

     $\rho_{hg}$=13600

So 101828.67=$13600\times 9.81\times h_{hg}$

$h_{hg}$=0.763 m

So mercury barometer will read 30.04 in.