As a hurricane passes through a region, there is an associated drop in atmospheric pressure. If the height of a mercury barometer drops by 21.4 mm from the normal height, what is the atmospheric pressure (in Pa)? Normal atmospheric pressure is 1.013 ✕ 105 Pa and the density of mercury is 13.6 g/cm3 (NOTE: This is g/cm^3, not SI units of kg/m^3).

Respuesta :

Answer:

The atmospheric pressure is [tex]9.845 \times 10^4\ Pa[/tex]

Explanation:

There are two ways of solving this exercise:

1)

In physics you can find that mmHg is a unit of pressure.

Pressure = Force/area.

If you consider the weight of mercury as your force (mass* acceleration of gravity = density*volume* acceleration of gravity ), then

[tex]P =\frac{\rho Vg}{A} = \frac{\rho Ahg}{A} =\rho g h[/tex]

where h is the height of the mercury column and rho its density.

[tex]\Delta P= P_{atm} - P_{hur} = 21.4\ mm Hg[/tex].

if normal atmospheric pressure is [tex]1.013 \times 10^5\ Pa = 759.81\ mmHg[/tex]

then the pressure in the presence of the hurricane is

[tex]P_{hur} = 759.81 - 21.4 = 738.41\ mmHg = 9.845 \times 10^4\ Pa[/tex]

2)

Considering the definition of pressure

[tex]\Delta P = \rho g h[/tex]

where [tex]\rho = 13.6\ g/cm^3[/tex], [tex]g = 9.8\ m/s^2 =980\ cm/s^2[/tex] and [tex]h = 21.4\ mm = 2.14\ cm[/tex].

[tex]\Delta P = P_{atm} - P_{hur} = 28521,92\ g/cms^2 = 2852,192\ kg/ms^2[/tex], where [tex]kg/ms^2 = Pa[/tex].

if

[tex]P_{atm} = 1.013 \times 10^5\ Pa[/tex],

then

[tex]P_{hur} = 1.013 \times 10^5 - 2852,192 =9.845 \times 10^4\ Pa[/tex].