Pressure

When a liquid is held in a container, it exerts pressure on the container… In what direction does the pressure act? Does the water flow out of the aquarium when there is a crack? Does the density of the liquid affect its pressure?

The pressure at a point in a liquid, acts equally in all directions

Weakest jet of water

Strongest jet of water

The pressure at a point in a liquid, at a particular depth, acts equally in all directions The pressure in a liquid increases with depth Weakest jet of water

Strongest jet of water

Which figure that the pressure exerts to same?

water

P

P

water

water

P

P

water

water

P

h

P

water

The pressure at a point in liquid depends on its vertical distance from the surface of the liquid, h

Pls answer !! !

What about if different shape ???

What about if different shape ???

Liquid pressure does not depend on the shape, or surface area of the liquid

How about density of the liquids ?

water

x1

A liquid with a higher density exerts a higher pressure

oil

x2

Become more higher

thick wall High pressure

Pressure in Liquids • The pressure in a liquid increases with depth • The pressure at a point in liquid depends on its vertical distance from the surface of the liquid, h • Liquid pressure does not depend on the shape, total mass, or surface area of the liquid • A liquid with a higher density exerts a higher pressure, ρ • The pressure in a liquid is affected by the force of gravity, g

FORMULA

m= ρV

F= W = mg

= Ahρ

= Ahρg

Pressure, P = W A = Ahρg A = hρg

P = hρg Pascal(Pa) = 1 Nm`-2

CLASS… LET’S DO SOME ACTIVITIES…

• First group will be discussing the question no.1. • Group 2 will be discussing the question no.2. • Group 3 will be discussing the question no.1. • Group 4 will be discussing the question no.2.

water coin

10m

6.5m

Congratulations! 10m

Answer

5m

Figure (a) = 65 kPa

coin

Figure (b) = 35 kPa

1.5m

water Water density = 1000 kg/m

3

Bottle shutter

3

Coin density = 0.01 kg/m g = 10 N/kg

Calculate the additional pressure exerted by the water at the coin shown on figure above?

APPLICATION OF PRESSURE IN LIQUIDS a)

f)

b)

g)

c)

h)

d)

i)

e)

j)

Which picture shows an application of pressure in liquids?

h)

Application of pressure in liquids

f)

Water tank position high above the ground b)

Safer model of dam

j)

Tilted container

Receiving intravenous drips of certain fluid

The pressure of water at a depth of approximately 4000m under the sea is about 400 times greater than the pressure at sea level. A pressure of this magnitude will crush the bodies of humans and ships unless they are enclosed in special equipments.

Homework: Exercise 3.2, Page 84 – 85, Question 1 & 2.

THE

DON’T FORGET TO MAKE A REVISION !!!! END

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