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Tufts OpenCourseware
Author: Fulcrum Institute Development Team


Challenge 1

Here is a picture of a metal rod with several positions along the rod marked by letters.

The rod has been sitting out on the table all morning and is at room temperature. At noon (say) you place position A on the rod in contact with a pot of boiling water. The water in the pot continues to boil as you monitor the temperatures at points A, B, C, and D for next 15 minutes.

Sketch graphs of how you think the temperature will vary from noon to 12:15 at points A, B, C, and D.

What would a histogram (bar graph) of the temperatures at points A, B, C, and D look like at noon? At 12:15?

Will the bar come to thermal equilibrium? Why or why not?

Challenge 2

Here is a picture of two rods that are both made of the same material.


Initially the bars are at room temperature. Then at noon we apply heaters to the left end of the bars. Once the heaters are applied they are left in place and continue to heat the bars. Three people get into an argument about which bar will have its right end heat up the fastest.

Person A says the thinner bar will have its right end heat up fastest.

Person B says the right ends of both bars will heat up at the same rate.

Person C says the thicker bar will have its right end heat up fastest.

With whom do you agree and why?

Challenge 3

You no doubt know that metals tend to be rather good thermal conductors compared to say wood or glass. (You wouldn't make potholders out of aluminum or copper!) Using what you know or can find out about the structure of matter on a microscopic scale, why do think this might be?