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Reporter: Hsieh, Tsung-Lin

Reporter: Hsieh, Tsung-Lin. Question. A wire with weights attached to each end is placed across a block of ice. The wire may pass through the ice without cutting it. Investigate the phenomenon. Outline. Experimental setup Typical results Hypothesis Pressure effect Weight

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Reporter: Hsieh, Tsung-Lin

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Presentation Transcript

  1. Reporter: Hsieh, Tsung-Lin

  2. Question • A wire with weights attached to each end is placed across a block of ice. • The wire may pass through the ice without cutting it. • Investigate the phenomenon.

  3. Outline • Experimental setup • Typical results • Hypothesis • Pressure effect • Weight • Thermal conductivity • Curvature • Other effect • Summary

  4. Experimental Setup Ice Camera Weights

  5. Typical Result • The wire position is obtained by MATLAB program. Duration: 1 hr

  6. Pressure Effect • Ice under the wire tends to melt. Heat

  7. Wire pressure Schematic Phase Diagram Pressure Liquid Atmospheric pressure Ice Solid Gas Temperature

  8. Wire pressure Hot Cold Schematic Phase Diagram Pressure Ice+Water Absorbing heat Cutting Liquid Atmospheric pressure Solid Gas Temperature

  9. Hot Cold Schematic Phase Diagram Pressure Releasing heat Liquid Atmospheric pressure Ice Solid Gas Temperature

  10. Weight Thermal conductivity Curvature Hot Cold Pressure effect

  11. Speed at Center • Speed of the center of the wire after it sinks into the ice. distance

  12. Weight Stainless steel wire 0.4mm • 3kg: 0.11 • 4kg: 0.18 • 5kg: 0.26 • 6kg: 0.30 • 7kg: 0.39 • 8kg: 0.49 (cm/min)‏

  13. Weight vs. Speed at Center Stainless steel wire 0.4mm Pressure l s g Temperature

  14. A l d Mathematical Estimation • Heat conducting rate: • From Clausius-Clapeyron equation, • Center speed upper limit • Pressure effect plays an important role.

  15. Hot Cold

  16. Material vs. Speed at Center Thermal Conductivity (W/m-K)‏ • Aluminum : 235 • Steel : 16.3 speed: 0.34 cm/min speed: 0.30 cm/min • Good thermal conductor cuts faster.

  17. Water Flow Video

  18. Pressure and Curvature T T θ θ r θ θ d Cross-section of the Wire Ice

  19. Cutting Speed • After the whole wire sinks into the ice: Pressure effect dominates External heat input is more significant Left side center

  20. External Heat Effect • Water melts due to external heat input • It can solidify again because the temperature inside the ice is below 00C (-150C~ -0.60C). Hot Cold External heat

  21. Summary • The wire passes through the ice • Pressure effect • External heat effect • The ice regelates (without being cut) • Pressure releases • Temperature inside the ice is below 00C

  22. Thank you for your attention.

  23. Ambient Temperature • The “speed at center” is almost constant. • Repeatable in different temperature (230C~280C). • Ambient heat can be neglected.

  24. Weight • 6kg: 0.12 • 4kg: 0.06 • 3kg: 0.05 (cm/min)‏

  25. Temperature inside the Ice

  26. Time interval: 5 min

  27. Time interval: 5 min

  28. Curvature vs. Speed • At the Beginning of Cutting: Pressure effect dominates Left side center

  29. Patterns formed on regelated ice

  30. Speed v.s. Curvature –at time 1 • In the middle of the ice, speed is positively related to the curvature. • The speed is faster at both side because of external heat. Fig. Acceleration Fig. Speed of the whole wire

  31. Speed v.s. Curvature –at time 2 • In the middle of the ice, speed is positively related to the curvature. • The speed is faster at both side because of external heat. Fig. Speed of the whole wire Fig. Acceleration

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