Question

Atmospheric pressure is ______ $N{{m}^{-2}}$ at sea level.
A.$2.026\times {{10}^{5}}$
B.$1.013\times {{10}^{5}}$
C.$3.039\times {{10}^{5}}$
D.$1.013\times {{10}^{6}}$

Answer 1

Hint: Atmospheric pressure is also called barometric pressure. It by definition is the pressure exerted by the atmospheric column or the air column that is present above the specified area. Atmospheric pressure at sea level is one standard atmosphere and we are supposed to find its value in $N{{m}^{-2}}$.

Formula used:
$1Pa=1N{{m}^{-2}}$

Complete answer:
We have many different systems of units in which atmospheric pressure could be expressed. The value of what we call standard sea-level pressure is 760mm of mercury, $1013.25\times {{10}^{3}}$ dynes per square centimeter, 14.70 pounds per square inch, 1013.25 millibars, or simply one standard atmosphere which is 101.325 kilopascals.
But in this question we are asked to find the atmospheric pressure in $N{{m}^{-2}}$ . So, let us convert one standard atmosphere into a value in$N{{m}^{-2}}$ .
As we know, $1Pa=1N{{m}^{-2}}$
One standard atmosphere= 101.325 kilopascals
$101.325KPa=101.325\times {{10}^{3}}N{{m}^{-2}}$
Therefore, atmospheric pressure at sea level measured in $N{{m}^{-2}}$ is $1.013\times {{10}^{5}}N{{m}^{-2}}$.

So, the correct answer is “Option B”.

Additional Information:
We should know that a very minute change in this value largely influences the wind and storm pattern of the planet.
We know, atmospheric pressure is just like any pressure- the force per unit area. But, here the force is exerted by the atmospheric column or the air column above a body. If you are wondering how this pressure is measured, it is measured using a mercury barometer. In this device the height of a column of mercury balances the weight of the column of atmosphere and hence measurement is taken. Apart from that we have an android barometer. In this device the sensing element is one or more hollow, partially evacuated, corrugated metal disks which are supported against collapse by an inside or outside spring; when a change in shape of the disk occurs as a result of changing pressure, we could record using a pen arm or a clock driven revolving drum.

Note:
There are standard values for quantities like atmospheric pressure at sea level. But, we should look at the unit in which it is asked in the question. As mentioned in the solution, there are plenty of units in which we could express one standard atmosphere, each value very different from the other.