Backwards-faded scaffolding laboratory/presentation: heat transfer laws

Anybody know who these guys are?
(Mr. Heat Miser, Mr. Cold Miser.)

(This is the twelfth Astronomy 210L laboratory at Cuesta College, San Luis Obispo, CA. This course is a one-semester, optional adjunct laboratory to the Astronomy 210 introductory astronomy lecture, taken primarily by students to satisfy their general education science transfer requirement.)

Let's consider different examples, both edible, and non-edible, of heat transfer phenomena--later you'll determine which heat transfer law(s) apply in each of these cases (Newton's Law of Cooling, Bergman's/Allen's Rule, Convection Law).

Nothing cuter than baby penguins snuggling to stay warm. Especially when they tuck their heads in, and put their wings around their buddies. (Wait--edible, or non-edible?)

The infamous Cooper Cooler™, where a tray of ice, a cup of water are added, and by spinning a soda can, it renders it ice cold in just 60 seconds in this infomercial. Just three easy payments of $19.99, shipping and handling and applicable state and local taxes extra.

Read those directions, and watch the clock--that ginormous turkey is going to require more cooking time.

Too hot? Blow on it cool it off.

And why is Earth geologically active today, while the other terrestrial planets, such as Mars, currently geologically dead?

Which snowman will melt fastest?

So think about these examples, and determine which heat transfers apply to each of these cases.

The second part of this laboratory is actually demonstrating these heat transfer laws, and also coming up with an experiment to answer a heat transfer law research question.

You'll have various size beakers, thermometers, trays, tap water, scalding hot water from a coffee percolator (caution!), and ice available for your use...

...along with empty plastic water bottles, and of course, a few Cooper Coolers™.

EQUIPMENT
      thermometers
      plastic trays
      Cooper Cooler(TM) Rapid Beverage Chiller
      large/small beakers
      percolator (plug in to heat water 30 minutes prior to lab)
      ice, ice chest
      empty water bottles with caps (undented, uncrushed)

BIG IDEA
Heat loss over time of astronomical objects such as star and planet interiors depends on several laws of energy transfer:

• Newton's Law of Cooling:
  Rate of heat loss of an object is proportional to the temperature difference between itself and its surroundings. (Greater temperature differences between an object and its surroundings mean faster heat transfers; smaller differences have slower transfers.)
  
• Bergman's Rule (or Allen's Rule):
  Rate of heat transfer to/from an object is proportional to the ratio of its volume to its surface area. (Small objects have greater surface area per volume ratios and faster heat transfers, large objects have lower surface area per volume ratios and slower heat transfers.)
  
• Convection Law:
  Rate of heat transfer to/from an object is dependent on the amount of convection within itself and in its surroundings. (More convection results in faster heat transfer, less/no convection results in slower heat transfer.)

GOAL
      Students will be guided through discussions and demonstrations of heat transfer laws, and later conduct inquiries about the relative dependence of heat transfer rates on various factors.

TASKS
(Record your lab partners' names on your worksheet.)
1. Exploration

1. Fill a small and a large beaker with same temperature hot water from the coffee percolator. Prepare an ice water bath in a plastic tray (but with not so much water that small beaker would float when placed into the ice bath). Record the initial temperatures in each beaker, and place each beaker into the ice water bath for at least 10 minutes. Set this experiment aside.
   
   
2. Several real-life observations of heat transfer phenomena are listed below. For each phenomenon, determine which heat transfer law(s) are demonstrated, and summarize your findings in a list(*). (You should come back to this list later in the laboratory for revisions/completion, if necessary.)
   
   
   
   1. Emperor penguin babies huddle together in order to stay warm.
      
      Heat transfer law(s), and explanation: _________.
      
      
   2. A room temperature bottle of wine will take 60 minutes to chill to a proper serving temperature when left in the freezer, while it chills "10 times faster" spinning in circulating ice water in a Cooper Cooler(TM) Rapid Beverage Chiller (*.html) appliance.
      
      Heat transfer law(s), and explanation: _________.
      
      
   3. The cooking time for a turkey depends on its weight (allrecipes.com):
      
      

      Weight of unstuffed bird (lbs):	Roasting time, (hrs):
      10-18 lbs	3 to 3-1/2 hours
      18-22 lbs	3-1/2 to 4 hours
      22-24 lbs	4 to 4-1/2 hours
      24-29 lbs	4-1/2 to 5 hours

      
      Heat transfer law(s), and explanation: _________.
      
      
   4. Blowing on a hot spoonful of soup to make it cooler.
      
      Heat transfer law(s), and explanation: _________.
      
      
   5. Earth is still geologically active today, while Mars is no longer geologically active.
      
      Heat transfer law(s), and explanation: _________.
      
      
   6. Small snowmen melt faster than larger snowmen.
      
      Heat transfer law(s), and explanation: _________.
      
   
   
3. After at least 10 minutes have elapsed, simultaneously record the final temperatures for the small beaker and the large beaker. Summarize your temperature data in a table(*).
   
   

   Beaker size:	Initial temperature (° C):	Final temperature (° C):
   Small
   Large

   
   
4. Record the volumes of water in the small beaker and the large baker. Measure the diameters of the small beaker and large beaker, and also the heights of the water in the small and large beaker. Calculate the total surface area of the water in each beaker by approximating its size as a box: 2×(diameter × diameter) + 4×(diameter × height). Summarize your data in a table.
   
   

   Beaker size:	Water volume (mL):	Beaker diameter (cm):	Water height (cm):	Surface area (cm^2):
   Small
   Large

   
   
5. Calculate the surface area per volume ratios for the small beaker and the large beaker.
   
   Small beaker surface area per volume ratio = __________ cm^2/mL.
   Large beaker surface area per volume ratio = __________ cm^2/mL.

2. Does Evidence Match a Given Conclusion?
      Discuss whether your data from the previous activity adequately demonstrates a heat transfer law or laws, and specify which law(s). Explain your reasoning and provide specific evidence from data, with sketches if necessary, to support your reasoning.

3. What Conclusions Can You Draw From This Evidence?
      A beaker of very warm water with a starting temperature of 46° C was placed into an ice-water bath, and the temperature of the water in the beaker was recorded at one-minute intervals.

Time (min):	Beaker water temperature (° C)
0 min	46° C
1 min	34° C
2 min	26° C
3 min	(Forgot to record)
4 min	21° C
5 min	19° C
6 min	16° C
7 min	14° C
8 min	11° C
9 min	10° C
10 min	9° C

      What conclusions and generalizations can you make from the information given above in terms of "How does the change in temperature of warm water in a beaker over time adequately demonstrate a heat transfer law or laws?" Explain your reasoning and provide specific evidence, with sketches if necessary, to support your reasoning.

4. What Evidence Do You Need to Pursue?
      Describe precisely what evidence you would need to collect in order to answer the research question of, "How much would a constant breeze across the surface of hot water (such as coffee or tea) cool it off faster than if there were no breeze?" You do not need to actually complete the steps in the procedure you are writing.
      Create a detailed, step-by-step description of evidence that needs to be collected and a complete explanation of how this could be done--not just "place a cup of hot water next to a fan," but exactly what would someone need to do, step-by-step, to accomplish this. You might include a table and sketches--the goal is to be precise and detailed enough that someone else could follow your procedure.

(At this point you should go back and revise/complete the explanations for the heat transfer laws in 1(b).)

5. Formulate a Question, Pursue Evidence, and Justify Your Conclusion
      Design an answerable research question, propose a plan to pursue evidence, collect data, and create an evidence-based conclusion about an aspect that you have not completed before, in order to demonstrate a heat transfer law. (Have your instructor approve your whiteboard research question before proceeding further.)
      Research report summary on whiteboards/poster paper, to be worked on and presented to the class as a group, should include:

1. Specific research question.
   
2. Step-by-step procedure to collect evidence.
   
3. Data table and/or results.
   
4. Evidence-based conclusion statement.