Transcript Air Pressure Activities

Air Pressure Activities
A.Inverted Glass
In your notebook:
B.Stop the Leak
C.Collapsing Can
D.Fastest Drinker
1. Diagram of set-up
2. Description of results
3. Explanation/principle
involved
Air Pressure
Air Pressure
• Air Pressure is
a measure of the
force of the air
pressing down on
the earth’s surface
Air Pressure can vary at any
particular point on the Earth
depending on the density of the air
Density = mass / volume
Title: Activity 1. Inverted Cup
Challenge:
Date: Feb. 2010
1.
Fill a cup with water.
2.
3.
Cover the cup with an index card.
Invert the cup. What happened?
Does the water spill out of the cup? Explain (using
concepts on pressure)
Results and
Explanation:
Summary:
Inverted Cup
cardboard
Air Pressure
When cup is completely
filled with water, no air is
left in cup, thus no air
pressure. The inverted
cup can therefore hold
water up because the air
pressure is working
against the underside of
the cup.
There is higher air pressure outside pushing
upward than the inside of cup pushing downward.
Title: Activity 2. Stop the Leak
Challenge:
Solution:
Results and
Explanation:
Summary:
Date: Feb. 2010
How can you stop the leak in this soda can?
Stop the Leak
By plugging one of the holes, the
air inside stays the same because
outside air is prevented from
coming into the hole. The higher
water volume inside causes a
decrease in pressure. Thus,
outside air pressure (which is
greater) pushes against the water
and prevents it from flowing out.
Air cannot
go in
Liquid
cannot
flow out
Air pressure outside of can is
greater than air pressure inside.
Title: Activity 3. Collapsing Can
Challenge:
Date: Feb. 2010
How can cause a can to collapse?
Solution:
Results and
Explanation:
Summary:
Explain the principle behind the collapsing can.
Collapsing Can
Before heating, the can was filled with water and air.
By boiling the water, the liquid changed into water vapor
 The water vapor or steam pushed the air that was inside, out of the can.
 In closing off the can, air is prevented from going back to the can.
 Cooling (water in basin) condenses water vapor back to water. All the
vapor which took up space inside the can turned into a few drops of
water, which take up less space.
 Pressure inside can drops allowing outside air pressure to push on the can and
crush it.
Title: Activity 3. Straw drinking race
Challenge:
Who can drink the fastest?
Regular straw
Results and
Explanation:
Summary:
Date: Feb. 2010
Modified straw
Explain the principle behind straw drinking.
When you drink liquid through a straw, is it
accurate to say the liquid is sucked up the
straw or pushed up the straw?
Straw Drinking Race
The higher pressure in
outside air pushes the
liquid up the straw in our
mouth
Sucking creates a
partial vacuum or a
lower pressure in
straw above the
liquid that we drink
The student with the
leaky straw cannot
create a vacuum above
the liquid, so the liquid
is not pushed up.
Density = Mass / Volume
 Warm air is less dense than
cool air. Warm air rises. Cool air
sinks.
 Air at high altitudes is less
dense than air at lower altitudes.
Factors that affect
Pressure

Air
Temperature
Water Vapor
Elevation
TEMPERATURE AND AIR PRESSURE
HEAT
LESS AIR
PRESSURE
Molecules
move faster
Move apart,
become fewer
and weigh less
HIGH TEMPERATURE,
LOW AIR PRESSURE
LOW TEMPERATURE,
HIGH AIR PRESSURE
AMOUNT OF WATER VAPOR
consists of
air and
water
molecules
More water vapor means
less air molecules
LOW AIR PRESSURE
DRY AIR = HIGH AIR PRESSURE
Factors Affecting Air Pressure
FACTOR
Density
Density
Temperature
Temperature
Water Vapor
Water Vapor
Altitude
Altitude
Increase/Decrease Air Pressure
Measuring Air Pressure
Types of Barometer
Air Pressure is
Mercury Barometer
measured by an
instrument called
Aneroid
Barometer
Air pressure
increases,
column of
mercury rises

Air pressure
decreases,
column of
mercury drops

Air Pressure & Weather
High pressure generally
means fair weather
Air mass in upper
atmosphere
No clouds
Layer of Air
Warm,
moist air
cannot rise
Low pressure generally
means cloudy, rainy
weather
Air masses
move apart
Warm air
rises, clouds
form
QUESTIONS – use your
knowledge of air pressure to
explain the following situations



A falling barometer is followed
by several days of rainy weather.
Some people find it hard to
breathe at high altitudes.
A rising barometer indicates a
spell of cool dry weather.