How do power lines illustrate thermal expansion and contraction?
Factors: B13, C3, C4, C8, D1, E3, E7, F3, G1 Objectives: 1.1, 2.1 Assessment Techniques: 1, 3, 5, 7c Common Essential Learnings: Numeracy. Students are able to measure a very small change by the use of amplification. • Get a wide-mouthed large glass jar, like a restaurant-size pickle jar. Put it in a freezer or outside if the temperature is below freezing, so that the air inside the jar is cold. Immediately upon bringing it out of the fridge or while it is still outdoors, cover the mouth of the jar with a piece of a latex examination glove (available from a veterinary supply store) stretched as tightly as possible. Secure the cover with an elastic or string around the neck of the jar. Observe what happens to the latex as the air in the jar warms. Account for this phenomenon. Try heating the jar by placing it in a shallow pan of hot water. Then cool the jar by placing it in a pan of ice water or snow. What effect do these changes have on the latex seal? An alternate way to demonstrate t
