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Physical Science Lesson 4 What Do We Learn When We Look More Closely?

Investigating Static Forces in Nature: The Mystery of the Gecko. Physical Science Lesson 4 What Do We Learn When We Look More Closely?. Observing Surfaces. Consider the following surface interaction: Transparent tape on lab table

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Physical Science Lesson 4 What Do We Learn When We Look More Closely?

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  1. Investigating Static Forces in Nature: The Mystery of the Gecko Physical Science Lesson 4 What Do We Learn When We Look More Closely?

  2. Observing Surfaces • Consider the following surface interaction: • Transparent tape on lab table • Diagram and describe what is happening between the two surfaces. Image 4.6

  3. Adhesives • What did you do to ensure that the sticky side of the tape had the most contact with the desk? • Describe how your tape on the desk resisted removal. Is this a property of a liquid or solid?

  4. If both surfaces are hard: Only a small percentage of the apparent contact area is in real contact. apparent contact area real contact area Soft – Transparent Tape Hard – Shoe Hard – Desk Top hard Compliant Surfaces If one or both surfaces are compliant: A large percentage of the apparent contact area is in real contact. Image 4.3 Image 4.4

  5. Prediction Predict (using words and drawings) what you think the surface of the gecko’s foot looks like as we magnify the foot. Image 4.5 Image 4.6

  6. Gecko Foot “Up Close” Image 4.7 Kellar Autumn Each spatula is about 100 nanometers thick.

  7. Making Connections • Describe one or two ideas that you learned during this lesson. • Which range do gecko setae fit into? • Which force would make best use of these many points of contact?

  8. Flow Chart Flow Chart 1. How Can a Gecko Walk on a Ceiling? Scale: Visible Dominant Force: Gravity Tools: Eye 2. What Do We Mean When We Speak About Surfaces in Contact? Scale: Visible Force: Gravity Tools: Eyes • What Are Your Ideas About Small Sizes? • Scale: Visible/Invisible • Dominant Force: Varies • Tools: Eyes, Instruments • What Do We Learn When We Look More Closely? • Scale: Invisible • Dominant Force: Extremely Small, Large in Number • Tools: Special instruments (scanning tunneling microscope) 5. What Types of Forces Can Hold Objects Together? 7. How Do We Measure Forces at the Nano Level? 8. How Can a Gecko Walk on a Ceiling? 6. How MUCH Force Is Needed to Make an Object Stick? What Factors Affect the STRENGTH of Force Acting?

  9. Sample Student Drawings

  10. Sample Student Drawings

  11. Sample Student Drawings

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