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Just-in-Time
Teaching
FIE, October 21,
2005 |
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Question
You have just been served a scoop of macaroni and cheese on a plate. The food is too hot to eat.
- What would you do to cool the food via conduction?
- What would you do to cool the food via convection?
- What would you do to cool the food via radiation?
Answers
- Conduction, I would let the macaroni transfer its heat through the plate it was on, making the Mac cooler and the plate hot. Using convection, I would sit over my plate and blow on the macaroni, using the air flow I create with my breath to cool the macaroni. I don't understand how radiation would work here, I just can't get a good enough explanation from the book so that I can relay the information. I get somthing about energy transfer through electromagnetic waves, so does that maybe mean that if I were to stick the plate in front of the TV, the waves from the TV would cool the macaroni? I just don't quite get it.
- To cool the food via conduction I would use a sterile copper coil inserted into the food and travelling a short distance through the air to a cup of ice. because a coil creates more surface area to absorb heat, copper is one of the best conductive materials, allowing the wire to travel through the air will dissipate heat, and sticking the other end in ice will cool any heat thats left as well as conducting some coolness back a portion of the wire. To cool the food via convection I would use the fluid motion of air by setting a fan over the food to transfer heat from the hot solid food to the cooler fluid air. To cool the food via radiation I would just let it sit there and allow the heat to "radiate" from the high energy state of the food to the low energy state of the sourounding atmosphere. You can almost see the waves in the rising steam, and now I'm hungury and have to go.
- To cool the food using conduction I would seperate the macaroni and cheese so that the noodles can be more distant. That way, the denominator from equation 3-50 will increase, causing the fraction to lower in value. To cool the food using convection I would Stir the macaroni and cheese and I would blow on it. To cool the food using radiation I would increase the surface area.
