Question

The unit for pressure used in weather maps is millibar. 1 millibar is equal to
(A) $1000bar$
(B) $100kPa$
(C) $100Pa$
(D) $1atm$

Answer 1

Hint
Pa, bar and atm are units of pressure, along with standard prefix values of milli, we will convert 1 millibar to Pa. We know the values of standard units and prefixes like kilo-, milli- and so on. Using those, options A. and D. are eliminated as they are wrong.

Complete step by step answer
Bar is a unit of pressure and the relation between bar and pascal is:
$ \Rightarrow 1bar = {10^5}Pa$
And by standard notations we know, 1 mill is $\dfrac{1}{{1000}}$
Hence for 1 millibar, we will divide by 1000 to convert it into millibar
$ \Rightarrow 1millibar = \dfrac{{{{10}^5}}}{{1000}}Pa$
$ \Rightarrow 1millibar = 100Pa$
So, the correct option is (C); $100Pa$

Additional Information
Pressure is defined as force which is perpendicular to the surface per unit area. $P = \dfrac{F}{A}$, where F is the magnitude of normal force and A is the surface area. For fluid pressure, we can say that the thrust exerted by a fluid at rest per unit area which is in contact with it is called fluid pressure. The S.I. The unit of pressure is Pascal (Pa) or $newton/meter{e^2}$ . Pressure is a scalar quantity with dimensional formula as$\left[ {M{L^{ - 1}}{T^{ - 2}}} \right]$. ‘atm’, a unit is used to measure atmospheric pressure with the help of a barometer. The C.G.S unit of pressure is Ba which is equal to 1 dyne per square centimeter.
$1Ba = 0.1Pa$

Note
We know, $1millibar = 0.001bar$
To measure pressure millibars and atm can be used in meteorology and science,
$ \Rightarrow 1atm = 1.013 \times {10^5}Pa$
$ \Rightarrow 1atm = 1.013bar$
Other unit of pressure is torr and $1torr = 133Pa$
‘torr’ is a smaller unit of pressure and one torr is equal to one millimeter of mercury.
There are many units of pressure so proper units and prefix must be carefully observed for pressure calculations.