Some of our everyday environments are constructed for us as buildings. This project has concentrated on buildings. Other environments have been “built” for us, such as clothing, appliances for cooking, cars, roadways, and bridges. Our environment is filled with technologies constructed for our convenience and comfort. Heat transfer is involved with how many of these things work. For example, in the kitchen there are a large number of appliances and other equipment where heat transfer is central to how they work.
CorningWare or Pyrex cookware
“Cooktop” ranges have a special glass that covers the entire surface of the range. The electric heating elements are under this glass. A major feature of this design is that you have smooth surface to clean. However, you also have surface that can be touched in the areas not directly affected by the heating elements. This suggests to me that heat transfer is by radiation to the cook top and/or the pan. The cooktop does not conduct heat very well. It is, I think, derived from material like CorningWare or Pyrex, which can withstand enormous variations in temperature. It evolved from materials originally developed for a U.S. ballistic missile program, and Stookey’s research involved heat resistant material for nose cones. Here is some interesting reading: http://www.bookrags.com/research/glass-heat-resistant-woi/
You can conduct this activity as an investigation. You could stimulate questions from students by talking about pans were food sticks when you cook. You can describe noticing an interesting pattern on the bottom of a particular pan. What caused this pattern?
Here is the activity and an explanation. For an investigation, generate discussion from students and suggestions for further testing so that they construct the explanation.
Place a CorningWare bakeware on the stove. Sprinkle flour over the bottom of the CorningWare and turn on the heating element or gas. The flour will brown in the shape of the element because CorningWare does not conduct heat very well. It gets hot where the element is but does not spread the heat. It is good for going from freezer to oven but on the stove, you need something like water in the container to circulate the heat.
Conduction [with connection to convection and radiation]
Next Generation Science Education Standards
Scientific and Engineering Practices:
– Developing and using models
– Planning and carrying out investigations
– Constructing explanations (for science) and designing solutions (for engineering)
– Engaging in argument from evidence
– Cause and effect: Mechanism and explanation
– Energy and matter: Flows, cycles, and conservation
– Structure and function
- Of what benefit is it to make heat resistant glass?
- What other features would be helpful to design into glass? [think of windows; think of glass in big buildings; think of different kinds of situations where you need protection]
- What is the difference between glass and plexiglass?