Air Pressure

Overview:

        This activity is geared toward students who have prior knowledge of how our atmosphere works.  Everyone knows that the atmosphere is made of gases and this lesson plan will specifically talk about air pressure.  It is amazing to know that the pressure our atmosphere applies to us and everything on Earth is14.7 pounds per square inch, or about a ton per square foot.  That is amazing to know that we can withstand such extreme pressure!  Air pressure is everywhere.  Think about how drinking out of a straw works.  Have you ever thought about it?  Many people do not know that you are not really sucking up the liquid but your mouth is removing air pressure built up in the straw and allowing the pressure outside of the straw, that is pushing on the liquid, to push the liquid into your mouth.  Also, air pressure can affect the bounce of a ball.  Air pressure effects many everyday things that can go unnoticed.  I challenge you to make a list of everyday objects that can be effected by air pressure after doing this lesson plan.  Students will also be able to wow their family and friends with this new information they will learn about in this lesson plan.

Grade: 9 th

Length: 3 hrs

Objectives:

        Students will apply the dry air pressure formula        P = Pd + Pv

where:  P = total pressure

                                                                        Pd = pressure due to dry air

                                                                        Pv = pressure due to water vapor

        Students will understand that as air is heated or cooled the molecules will become                 farther apart or closer together

Standards:

Science

CLE 3202.1.8 Investigate relationships among the pressure, temperature, and                 volume of gases and liquids.

Math

0706.4.5 Solve problems using ratio quantities: velocity (measured in units such as         miles per hour), density (measured in units such as kilograms per liter), pressure                 (measured in units such as pounds per square foot), and population density                 (measured in units such as persons per square mile).

Procedure:

• Day 1

• Give all students a cup with water and a straw.

• Have the students drink using the straw.
• Now have the students tell how they are able to use the straw to drink the liquid.
• Talk about objects we use everyday that can be affected by air pressure

• Basketballs full of air

• In higher cooler elevations the ball may not bounce as high because the molecules are close together.

• Straws as previously stated

• Pressure pushes liquid through straw because your mouth creates an area for the pressure in the straw to go so the liquid will come up

• Weather

• Now teach the lesson of how air pressure relates to weather.

• Air pressure is 14.7 pounds per square inch, or about a ton per square foot
• Higher the altitude the lower the air pressure because the air is thinner and less dense
• The movement of air from more dense to less dense creates winds
• Changes in air pressure are measured on an instrument called a barometer. Most barometers give a reading in millibars (mb for short). Readings over 1010 mb indicate high pressure.
• Air Pressure is made up of molecules
• Warm temps make the molecules spread out added with water vapor, creates clouds
• Cool temps and air make the molecules close together, this creates dense clouds and possible storms

• Day 2

• Do experiments
• Talk about outcomes
• Assessment

• Use questionnaire on Water and Air Pressure activity and mathematical aspect using air pressure problems

Defying Gravity

Groups of 2

Materials:

• Jar with no cracks in lid
• Sturdy playing card or another card object to cover the mouth of the jar
• Water
• Small tub

Procedure:

Over a sink or small tub:

• First fill the jar ⅔ full of water
• Lay the card fully covering the mouth of the jar
• Invert the jar with the card still in place
• Without tipping the jar, slowly remover your hand
• The card should stay

Reason:

The air pressure pushing up on the card is greater than the water pushing down on the card.  Also, where the water is polarized, molecules connected together, the water stays in the jar.

Sucking an Egg                                                                                 Groups of 2

Materials

• Hard-boiled egg without the shell
• A bottle thats opening is slightly smaller than the egg, such as a sobe bottle
• A match

• This is a really simple experiment that does not require a lot of explanation. First, place the bottle on a flat sturdy surface.

• Have an adult light a match and place the match inside the bottle while the match is still burning.

• Place the hard-boiled egg on top of the bottle while the flame is going and watch as the egg gets sucked into the bottle.

Reason Why:

When the flame was lit, there was an expansion of gasses because when you heat up air the air pressure is thinner causing the air to expand. When the flame went out, the expansion collapsed causing a vacuum suction to occur. This is why they egg was suck in. It was the loss of air pressure.

Bibliography:

http://www.rcn27.dial.pipex.com/cloudsrus/pressure.html

http://www.ehow.com/how_4594591_suck-egg-bottle.html#ixzz1JvUUaXGA