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Investigation 4-3

Investigation 4-3

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Transcript

  • 1. Heating Earth The Pressure is On! 4-3
  • 2. Atmosphere
    • What have we discovered about air so far?
      • Is matter - has mass & occupies space
      • Is mixture of gases - mostly nitrogen & oxygen
      • Made of individual nitrogen & oxygen molecules flying through space
      • Can heat up & cool down
      • Gets denser as it cools, less dense as it warms
  • 3. Atmosphere
    • Planet Earth is completely surrounded by a thin layer of air.
      • Called the atmosphere
      • Extends up about 300 miles above Earth’s surface
      • Most of the air is in first 9 miles
  • 4. Investigating Air
    • Use syringe and plastic tube to find out more about air.
    • Answer the following questions:
      • What happens to air in the syringe when you push and pull on the plunger?
      • What can air do?
  • 5. Air & Syringes
    • Record your observations on notebook sheet
    • Try investigations on sheet - record observations and any questions
    • What observations did you make?
    • What questions do you have?
  • 6. Air Observations
    • When you clamp the tube closed and push the plunger down, what happens to the air?
    • Is there more air, less air, or the same amount of air in the syringe when the air is pushed into a smaller space?
      • How do you know?
    • What happens when you let go of the plunger after pushing it down?*
    • What do you think happens to the air when it is pushed into a smaller space?
    • What happens to push the plunger back out when you release the plunger?
  • 7. Compression and Pressure
    • When you push on the plunger, the air is forced into a smaller space.
      • The air is compressed
      • Same amount of air is still in the syringe when compressed
    • Compressed air pushes back with a force equal to the force compressing it.
      • Pushing force is called pressure
      • If force on plunger is released, the pressure in the compressed air will push the plunger out
  • 8. Molecular Model of Air
    • Air is made of tiny particles
      • Called molecules
      • Made mostly of Nitrogen & Oxygen molecules
      • So tiny you can’t see them
      • Free to move around - not attached
      • Lots of space between molecules in gases
  • 9. Bottle Demonstration
    • What do you think will happen to the bottle when I suck on the tube?
    • Why did the bottle get crumpled? What caused the bottle to collapse?*
    • Bottle collapsed and crumpled for the same reason a syringe plunger moves in and out “by itself” when connected to a second syringe.
    • What causes plunger in syringe #2 to slide in and out when you push and pull the plunger in the syringe #1?
  • 10. Atmospheric Pressure
    • Syringe has a little bit of air trapped between rubber tip of plunger and clamp.
      • Air molecules are flying around & banging into each other, sides of syringe, & plunger tip
      • Air molecules outside the syringe also flying around; banging into each other, outside of syringe, & back side of syringe plunger.
      • Banging produces pressure
      • Air inside syring pushes on inside of syringe; air outside syringe pushes on outside of syringe
  • 11. Atmospheric Pressure
    • Applying force to plunger to pull it out.
      • Release plunger, it slides back into barrel by itself
      • What makes the plunger go back into the barrel where it started?
    • Atmospheric Pressure!
      • Pull plunger = larger space but same number of molecules
      • Pressure is less inside syringe
      • Pressure is greater outside syringe
      • Plunger is pulled back until pressure is equal both inside and outside
  • 12. Atmospheric Pressure
    • Atmospheric pressure is pressure due to the mass of air pulled to Earth by gravity.
      • Same in all directions - upward, downward, & to the sides
      • Air is pushing on every side of you & everything else on Earth’s surface with equal force
    • Complete Atmospheric Pressure at Work sheet
  • 13. Vocabulary
    • Compress
      • squeeze (air) molecules into a smaller volume (space)
    • Pressure
      • force or push casued by moving molecules
    • Atmosphere
      • layer of air around Earth
    • Atmospheric pressure
      • Force applied in all directions by the air in Earth’s atmosphere
  • 14. Content
    • What happens when air is pushed into a smaller space?
      • Air molecules move closer together, resulting in compressed air
    • What causes atmospheric pressure?
      • The weight of air
    • Homework: Read The Pressure is On! & Summary: Heating Earth and answer questions; I-check 4 on February 28th (14 & 12) or March 1st (15)
  • 15. The Pressure is On!
    • What is atmospheric pressure and what causes it?
    • Is atmospheric pressure higher on a mountaintop or at sea level?
    • Why did the bag of chips puff up over Tioga Pass?
    • Why was the empty water bottle crushed when they returned to San Francisco?
  • 16. Summary: Heating Earth
    • What causes uneven heating of Earth’s surface?
    • How does uneven heating of Earth’s surface results in convection currents?
    • What is atmospheric pressure and what causes it?
    • In what direction does atmospheric pressure push?