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Physical Science Lesson 8 How Can a Gecko Walk on a Ceiling?

Investigating Static Forces in Nature: The Mystery of the Gecko. Physical Science Lesson 8 How Can a Gecko Walk on a Ceiling?. Image 8.3 Spatula-Shaped Tips. Image 8.2 One Gecko Seta. Closer Look. Tape or Spatulas. Hard Surface. Tape and Spatula. (d). Image 7.4. 1. m.

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Physical Science Lesson 8 How Can a Gecko Walk on a Ceiling?

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  1. Investigating Static Forces in Nature: The Mystery of the Gecko Physical Science Lesson 8 How Can a Gecko Walk on a Ceiling?

  2. Image 8.3 Spatula-Shaped Tips Image 8.2 One Gecko Seta Closer Look

  3. Tape or Spatulas Hard Surface Tape and Spatula (d) Image 7.4 1 m Spatula-shaped tips on gecko seta interacting with a smooth surface Transparent Tape on Glass If one or both surfaces are compliant : Image 8.6 Image 8.5

  4. Play the “Hot Spots” Game to find out! http://dawn.jpl.nasa.gov/mission/ion_engine_interactive/lev2/index.html Or Charge Simulator:http://dawn.jpl.nasa.gov/mission/ion_engine_interactive/lev1/index.html How does the kind of charge on the particle affect the deflection of the positively charged particle? What Is Happening Between The Surfaces?

  5. 1. What is the effect of placing a negatively charged player (red dot) close to the path of the positively charged soccer ball (blue dot)? 2. What is the effect of placing a positively charged player (red dot) close to the path of the positively charged soccer ball (blue dot)? 3. What are your thoughts about the gecko seta surface and the ceiling surface as they relate to charges? What Did You Find Out From “Hot Spots?”

  6. Type of Interaction

  7. 4. What makes you think that these attractions are weak? 5. Are these permanent or temporary attractions? How long do they last? Questions

  8. + + - - - - + + - - + + + + - - + + - - - - + + + + + + - - - - Describe the Interaction Image 8.8 Image 8.9

  9. + + - - - + - + + + - + + - - + + - - + - - + - + + + + - - - - Describe the Interaction Image 8.10 Image 8.11

  10. – + – + Weak/Temporary Interaction Between Two Surfaces Image 8.13 Single Gecko Seta Probe Surface Image 8.12 Image 8.15 Image 8.14

  11. Animation

  12. Animation

  13. Which molecule has the most contact with the green molecule? Explain how shape affects the number of attractions between the object and the surface. Which molecule acts most like the gecko seta? Docking Animation Questions

  14. Describe the number and size of forces involved in gecko adhesion. What part of the atom moves in response to momentary charge rearrangements? Describe this interaction between the electrons of each atom. Describe the overall charge and how long the attraction lasts. What Is Your Answer?

  15. View the Nano in Nature video: http://www7.nationalgeographic.com/ngm/0606/feature4/multimedia.html Adhesion force consistent with electric forces Adhesion enhanced by sliding, regardless of speed Adhesion force mainly independent of humidity Adhesion effective underwater Geckos walk through dirt—it normally takes about 5 steps for a gecko to recover adhesive capability after walking through graphite lubricant. Research Summary

  16. 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 3. What Are Your Ideas About Small Sizes? Scale: Visible/Invisible Dominant Force: Varies Tools: Eyes, Instruments 4. 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? Scale: Visible/Invisible Dominant Force: Gravity Tools: Eyes and Hands 6. How MUCH Force Is Needed to Make an Object Stick? What Factors Affect the AMOUNT of Force Acting? Scale: Visible Force: Gravity, Adhesive Tools: Spring Scale • How Do We Measure Forces at the Nano Level? • Scale: Visible and Invisible • Dominant Force: Extremely Small, Large in Number • Tools: Atomic Force Microscope 8. How Can a Gecko Walk on a Ceiling? Scale: Visible and Invisible Dominant Force: Electric Forces Tools: Atomic Force Microscope

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