What Unit of pressure equal to 14.7 pounds per square inch?

Answer 1

This is called "standard atmospheric pressure" (equal to 1013 mbar or 101.3 kPa) and is a component of STP (standard temperature and pressure). It is the average pressure exerted on all objects, in all directions, by the air at sea level.

The weight of all the air above you, from where you're standing to the top of the

atmosphere, is naturally heavier on a whole table-top than it is on the tip of your

finger, because the table-top has more area, and it's under more air. So we don't

talk about the weight of air, because it depends on the area. We talk about the

pressure of air ... the weight on one unit of area, and that's the same no matter

how big the area is. Pressure tells how many pounds of air on one square inch (psi),

or how many newtons of air on one square meter (pascals). That's what barometers

are measuring.

Again, we're talking about the weight of all the air above you, from wherever you are

to the top of the atmosphere. So as you go higher off the ground, there's more air

below you, which means that the weight of air above you is less. That's why there's

less air pressure at high altitude ... water boils at a lower temperature in Denver,

and it's hard to breathe as you climb Mt. Everest. There's just as much oxygen

available in the air on the mountain, but your lung machinery needs it delivered

at the pressure down here, and doesn't work very well at the pressure up there.

Is there a normal, typical, average, standard number for air pressure ? We suspect

there must be, because we hear weathermen talking about "High pressure" and

"Low pressure" systems, so they must be comparing it to something.

We know that air pressure depends on the altitude, so if there's some number that's

considered "normal", it'll also involve a definite altitude.

Without getting into official scientific definitions, the numbers that approximately describe

'normal' atmospheric pressure include the following:

-- 14.7 pounds per square inch, measured at sea level

-- 101.3 kilopascals (100 thousand newtons per square meter), measured at sea level

-- 29.92 inches of Mercury

(the height of a tube of mercury that has the same weight as a tube of air

that covers the same area; this is the number from a barometer.)

Answer 2

Approximately 150 lbs per sq in.