Reporter Hsieh TsungLin Question A wire with weights

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 Thermal conductivity Curvature Other effect Summary

Experimental Setup Ice Camera Weights

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

Pressure Effect Ice under the wire tends to melt. Heat

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

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

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

Pressure effect Weight Thermal conductivity Curvature Hot Cold

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

Weight Stainless steel wire 0. 4 mm 3 kg: 0. 11 4 kg: 0. 18 5 kg: 0. 26 6 kg: 0. 30 7 kg: 0. 39 8 kg: 0. 49 (cm/min)

Weight vs. Speed at Center Stainless steel wire 0. 4 mm Pressure l s g Temperature

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

Hot Cold

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.

Water Flow Video

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

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

External Heat Effect Water melts due to external heat input It can solidify again because the temperature inside the ice is below 00 C (-150 C~ -0. 60 C). External heat

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 00 C

Thank you for your attention.

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

Weight 6 kg: 0. 12 4 kg: 0. 06 3 kg: 0. 05 (cm/min)

Temperature inside the Ice

Time interval: 5 min

Time interval: 5 min

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

Patterns formed on regelated ice

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. Speed of the whole wire Fig. Acceleration

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