Question

Explain Atmospheric Pressure In Detail

Answer 1

here's your answer ⭐

That pressure is called atmospheric pressure, or air pressure. It is the force exerted on a surface by the air above it as gravity pulls it to Earth. Atmospheric pressure is commonly measured with a barometer. ... Meteorologists describe the atmospheric pressure by how high the mercury rises.

hope it helps you

thanks ☺️

Answer 2

Atmospheric Pressure :

The Whole Earth is Surrounded By A Blanket of Air known As Atmosphere. The Atmosphere Extends up to a Height of about 1600 km. The Weight of all the Layers of Air Exerts a Force on the Surface of the Earth.

• The Force exerted on Unit Area of the Earth's Surface due to the Atmosphere is called Atmospheric Pressure.

Standard Atmospheric Pressure :

The Normal or the Standard Pressure is the average Pressure of the Atmosphere at Sea Level at 273 K and is Expressed as a Pressure of One Atmosphere (1 atm) . It is found that 1 atm Pressure can balance a column of Mercury 0.76 m High . Thus The Normal or Standard Pressure is 0.76 m Hg.

• We are not Aware of this Because Blood in our Body exerts a Pressure which is Slightly Greater than the Atmospheric Pressure

We Can Express it in Pascal as : 0.76 m Hg Pressure = ρgh

• ρ = Density of Mercury

• g = Acceleration Due To Gravity

• h = Height of Mercury Column

⇒ 0.76 m Hg Pressure = ρ × g × h

⇒ 0.76 m Hg Pressure = 13600 kg/m³ × 9.8 m/s² × 0.76 m

⇒ 0.76 m Hg Pressure = 13600 kg/m² × 9.8 s⁻² × 0.76 m

⇒ 0.76 m Hg Pressure = 13600 kg/m × 9.8 s⁻² × 0.76

⇒ 0.76 m Hg Pressure = (13600 × 9.8 × 0.76) kg/m × s⁻²

⇒ 0.76 m Hg Pressure = 101292.8 kg/m × s⁻²

⇒ 0.76 m Hg Pressure = 101292.8 Pa

⇒ 0.76 m Hg Pressure ≈ 10⁵ Pa (Approximately)

Thus : 1 atm = 0.76 m Hg = 10⁵ Pa

Note : If the Atmospheric Pressure (P₀) Acting on the Free Surface of Liquid is also Taken Into Account Then Total Pressure in a Liquid a Depth h = Atmospheric Pressure + Pressure due to Liquid Column

Measurement of Atmospheric Pressure :

The Instrument Used to Measure The Atmospheric Pressure is Barometer. It was Constructed By Torricelli in 1643. Meteorologists use barometers to predict changes in the weather.

Construction of Simple Barometer :

• It Consist of a Glass Tube With A Narrow Uniform Bore and of Length 100 cm or (1/100) m

• It is Closed at One End. The Tube is carefully Filled with Perfectly Pure and Dry Mercury so that No Air Bubbles are Left Inside the Tube

• Thumb is Placed Tightly on the Open End of the Tube and Then it is inverted into a Bowl containing Mercury

• The Thumb is Removed From Open End, Under the Surface of Mercury in The Bowl

• It is Observed that Some Mercury Flows Down, Thereby Creating an Empty Space which is Commonly Known as Torricellian Vacuum

• It is Found that At The Sea Level, The Vertical Height of Mercury Supported in The Tube is 76 cm above the Mercury Level in the Bowl

• When An Equilibrium is Established, We can Say that Pressure Exerted By 76 cm Vertical Height of Mercury Column is Equal to the Pressure Exerted by the Air Column at the Surface of Mercury in the Bowl.
• In Other Words, The Air Exerts As Much Pressure As Exerted by 76 cm of Vertical Height of Mercury Column