# Unit 3 Pressure from the air (yr 9)

```UNIT 3.3:-PRESSURE FROM THE AIR
Let’s look at how air can exert
pressure even though we can’t
see it.
LEARNING OBJECTIVES
9Pf3 Explain pressures in gases and liquids (qualitative
only).
Understanding the properties of pressure in air
Learning the concept of atmospheric pressure and its
standard value.
Understanding the functioning of a Barometer to measure
the atmospheric pressure.
Learning how we can use the manometer to measure the
pressure difference between gases.
STARTER QUESTIONS (PEER CHECK) :1. Does pressure exist in all states of matter? Explain why?
2. How does pressure exerted by solids differ from that
exerted by liquids?
3. Mention the ways in which pressure exerted by solids
can be altered.
4. Mention the ways in which the pressure exerted by
liquids can be altered.
5. Write down the pressure equation of solids and then of
liquids?
ANSWERS :1. Yes, pressure is exerted from all states of matter as they all are made up of particles.
The vibration or motion of these particles exert pressure on the surfaces.
2. Pressure in solids are exerted on the surfaces the particles are in contact with, like the
bottom of the book with exert pressure on the top of the table. Pressure of liquids acts
in all direction as the particles are moving and colliding in all directions.
3. By changing the area the force is applied on and also by changing the force ( if
possible)
4. By changing the type of liquid ( changing density) and by altering the height of the
liquid.
5. SOLID
LIQUID
watch?v=KndNN28OcEI
What are
the two
properties
of Air can
you see
that are
found in
liquids?
ANALYZE AND EXPLAIN WHY IN ONE
LINE
LETS LOOK AT A BAROMETER
EA
1atm = 760 mm ( Barometer)
1atm = 101 300Pa
1mb=100 Pa
HOME LEARNING (TIMMS)
Research on the difference between weather
and climate and how both are affected by the
changing air pressure and temperatures of the
earth’s atmosphere.
Include also the effects that the position of a
country on the globe and the continuing global
warming is having on the conditions of the
present weather and climate around the world.
```
Thermodynamics

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