6th Grade-Ch. 1 Sec 2 Air Pressure

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6th Grade-Ch. 1 Sec 2 Air Pressure

  1. 1. Ch. 1 Sec. 2 Air Pressure
  2. 2. properties of air <ul><li>1. mass </li></ul>
  3. 3. properties of air <ul><li>2. density = </li></ul><ul><li>mass/volume </li></ul>
  4. 4. properties of air <ul><li>3. pressure =force pushing on a surface or area </li></ul><ul><li>units of air pressure = </li></ul><ul><ul><li>inches of mercury </li></ul></ul><ul><ul><li>millibars </li></ul></ul>
  5. 5. barometer <ul><li>instrument used to measure changes in air pressure </li></ul>
  6. 6. barometer <ul><li>2 kinds: </li></ul><ul><li>1. mercury = glass tube open @ bottom end & partly filled w/ mercury </li></ul>
  7. 7. barometer <ul><li>2. aneroid = airtight metal chamber sensitive to changes in air pressure - smaller than mercury barometer </li></ul><ul><li>- doesn’t contain liquid </li></ul>
  8. 9. altitude <ul><li>elevation (distance) above sea level </li></ul><ul><li>air pressure ________ </li></ul><ul><li>as altitude increases </li></ul>decreases
  9. 10. <ul><li>higher the altitude-______ the air pressure </li></ul><ul><li>As air pressure decreases- density of air _________ </li></ul>decreases lower
  10. 11. The density of air decreases as altitude increases.
  11. 12. Air at sea level has more gas molecules in each cubic meter than air at the top of a mountain. 21% oxygen 21% oxygen
  12. 13. Measuring air pressure using an aneroid barometer High High High High or low pressure 1,024 mb 1,024 mb 1,023.5 mb Air pressure ? Sunny Tue. 3/23/10 69 Partly cloudy Mon. 3/22/10 79 0 sunny Fri. 3/19/10 Weather Day/Date
  13. 14. Make barometer <ul><li>Cover the top of the coffee can tightly with the plastic wrap, using the rubber band to hold it in place. (The cover should be a taut, airtight fit.) </li></ul><ul><li>Position the straw so that it lays across two thirds of the cover with the remaining length of the straw suspended over air. Tape in place. </li></ul><ul><li>At a 90° angle, fold one short end of the index card at about one inch from that end. Tape the folded end of the index card to the can behind the straw in such a way that allows you to make marks on the card every day. </li></ul><ul><li>Record the level of the straw onto the card. </li></ul><ul><li>For the next 10 days, at the same time each day, record the level of the straw while paying close attention to how changes in the weather affect the straw's level. </li></ul>
  14. 15. Demonstrate the &quot;Weight of Air.&quot; <ul><li>Place one end of the thin board on a table with slightly less than half the board hanging off the edge. </li></ul><ul><li>Lay a sheet of newspaper over the part of the board on the table. </li></ul><ul><li>Allow students to predict what would happen if the protruding end was struck as hard as possible. </li></ul><ul><li>Strike the protruding board as hard as you can. The paper will not move. If you hit hard enough, the stick will break. This is due to the air pressure that is exerted downward. Since the paper is flat against the board and table, no air is beneath the paper to counteract the pressure from above. </li></ul><ul><li>Calculate the surface area of the newspaper. (length by width) </li></ul><ul><li>Multiply the surface area by 14.5. The result will be the amount of air pressure exerted on the paper. </li></ul><ul><li>Have students predict what would happen if you pushed down on the board slowly. </li></ul><ul><li>Place your hand on the protruding piece of the board and slowly push down. </li></ul>

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