The Physics
Hypertextbook
Opus in profectus

# Conduction

## Problems

### practice

1. The cook pot shown in the photograph to the right is quite high class. Pots of this sort are usually manufactured by stamping a single sheet of heavy gauge stainless steel or aluminum in a powerful metal press. This one is different in that it was stamped from a "sandwich" of steel-copper-steel (note the copper core between the stainless steel bottom and sides). What advantage would such a complicated pot have over similar single metal pots when used in the kitchen? Why have a copper core? Why use stainless steel for the sides and bottom? What's the deal with this pot?
2. Write something else.
3. olive-oil.txt
A liter of warm olive oil was placed in a freezer and allowed to solidify. Temperature measurements were taken every six seconds for one hour (3,600 s). Determine its final equilibrium temperature.
4. Calculus problem. Show that Newton's law of cooling produces a temperature curve that decays exponentially.

### conceptual

1. These three conceptual questions are a part of a larger worksheet (heat-transfer.pdf).
1. Describe a food preparation activity that involves heat transfer by conduction and explain how the rate of this heat transfer is controlled by the behavior of or the decisions made by the cook.
2. Describe how a typical house in your neighborhood loses heat to or gains heat from the environment by conduction and explain how the rate of this heat transfer is controlled by the behavior of its occupants or by the way in which the building was constructed.
3. Describe how animals lose heat to or gain heat from their environment by conduction and explain how the rate of this heat transfer is controlled through physiological or behavioral adaptations.
2. Why can you hold your hands in a blasting hot oven for the few seconds it takes to remove a roast without feeling any ill effects, but if you touch the roasting pan for even a split second you'll wind up with a burn?

### numerical

1. The interior dimensions of a compact refrigerator are 46 × 46 × 82 cm. It is surrounded on all sides by 5 cm of polystyrene foam. At what rate does it lose heat to a 20 ℃ room if the interior of the fridge is kept at 4 ℃.
2. Which of the following radiant heating systems transfers heat to a 20 ℃ room at a faster rate if both are the same length?
hot water steam
temperature 70 ℃ 102 ℃
pipe material copper cast iron
pipe inner diameter 2.5 cm 3.0 cm
pipe thickness 1.0 mm 4.5 mm