# Liquid and Atmospheric

## Presentation on theme: "Liquid and Atmospheric"— Presentation transcript:

Liquid and Atmospheric
- Pressure - Liquid and Atmospheric Pressure Pressure Measurement Definition of Pressure by Rifki Irawan & Fiqri Hakim

Pressure F (N) force P (Pa) = Pressure = A (m2) area
Definition of Pressure Pressure is the force acting normally or perpendiculary per unit area F (N) force P (Pa) = Pressure = A (m2) area SI unit for Pressure is Pascal (Pa) = 1 N m-2

“ same force, different area, different pressure “
Weight = 100 N Area = 0.01 m2 Pressure = 10,000 Pa Weight = 100 N Area = 0.1 m2 Pressure = 1000 Pa “ same force, different area, different pressure “

Force = pressure x area = 100 Pa x 6 m2 = 600 N
Example 1. The wind pressure on the wall is 100 Pa. If the wall has an area of 6 m2, what is the force exert on it? To solve this problem, you need to rearrange the pressure equation: Force = pressure x area = 100 Pa x 6 m2 = 600 N

Area = 0.5 m x 1.0 m F = mass x gravitasi Pressure = force/area
Example 2. A concrete block has a mass of 2,600 kg. If the block measures 0.5 m length by 1.0 m width and 2.0 m height, what is the maximum pressure of the concrete block that can exert when resting on the ground? (g = 10 m · s-2) Area = 0.5 m x 1.0 m = 0.5 m2 F = mass x gravitasi = 2,600 kg x 10 m · s-2 = 26,000 N Pressure = force/area = 26,000 N / 0.5 m2 = 52,000 Pa

Liquid and Atmospheric Pressure
“A liquid exerts pressure because of its weight” Pressure acts in all direction Pressure increases with depth Pressure depends on the density of the liquid Pressure does not depend on the shape of the container

Volume liquid = base area x depth = A x h
Weight= mass x gravity mass liquid = density x volume =  x A x h “pressure of the liquid depends on the density of the liquid itself” Weight liquid = mass liquid x gravity =  x A x h x g mass Density = Weight liquid = Force of the liquid =  A h g volume Force liquid  A h g Pressure liquid = Area container A Pressure liquid =  h g

Pressure = ρhg = 1,000 kg/m3 x 2 m x 10 N/kg = 20,000 Pa Example 1.
If the density of water is kg/m3, what is the pressure due to the water at the bottom of a swimming pool 2 m deep? First, define the data which given Density= kg/m3 Height= 2 m Gravity= 10 N/kg Pressure = ρhg = 1,000 kg/m3 x 2 m x 10 N/kg = 20,000 Pa

Atmospheric pressure The athmosphere is a deep ocean of air which surround the earth. In some ways, it is like liquid: Its pressure acts in all directions. Its pressure becomes less as you rise up through it Unlike a liquid, air can be compressed.

Atmospheric pressure The pressure that will support a column of mercury mm hight is known as standard atmospheric pressure or 1 atmosphere (1 atm) 1 atm = Pa In weather forecasting we often used milibar (mb) 1 mb = 100 Pa

The instruments The mercury barometer
Atmospheric press the mercury up the tube because the space at the top of the tube has no air in it. mm Hg = 1 atm