Heat Transfer Experiment~

               This week’s experiment focused on the transfer of heat. When an object is heated up the molecules begin to vibrate faster and faster causing a rise in temperature and the heat is transferred through conduction, convection, or radiation. Conduction is the transfer of heat from a region of higher temperature to a region of low temperature by being transferred from molecule to molecule (Tillery, Enger & Ross, 2008). The second way to transfer heat is by convection which is the transfer of heat by movement of the warm matter (Laureate Education Inc, 2010). The third way to transfer heat is by radiation which is the transfer of heat through an empty space (Laureate Education Inc, 2010). All three of these methods of heat transfer were seen in this experiment. One of the materials I used was plastic wrap which allowed me to see what was happening inside the cup. After thirty minutes water vapor had condensed on the plastic wrap and was dripping down into the cup. When a liquid is heated it warms, expands, and evaporates. When the water vapor reached the material it came in contact with the cooler air causing the water vapor to cool and condense. When the water cools it falls thus creating a convection current inside the cup. Convection currents play a big part in the way the water was cooled down. By creating the current it allowed cooler molecules to return to the warm water cooling the molecules down faster. For another material I used tin foil which created an environment where conduction occurred. Using this material created an environment where the molecules did not have to move to transfer the heat after a certain period of time. The heat from the water and air trapped under the tin foil allows all the molecules inside as well as in the tin foil to heat up to a constant temperature. This keeps the water and air inside at a constant temperature which slows down the cooling process. Radiant heat transfer was also seen with this material because the heat could be felt when your hand was held over the cup.

            When I do this experiment again I would like to use materials that are more commonly used with keeping things warm. I would hold a class discussion for these common items and bring what them to class. These items can include Styrofoam cups, tin foil, plastic and glass containers. I think the Styrofoam cup would be the best insulator because it keeps hot liquid from burning your hand however, it would depend on what kind of lid was used. Overall, I still think tinfoil would be the best insulator. Different kinds of food also need to be kept warm so I would discuss with the class the most common foods they eat and home that need to be kept warm. This could include soup, hot dogs, noodles, or macaroni and cheese. I think these types of foods would act the same as the water except the more surface area the food has the faster the food will cool down. By including the students in the experiment set up they will make real life connections with the activity as well as the concepts and ideas being put to the test. By completing this experiment I would want my students to understand what the different types of heat transfer are, what a good insulator is, and how it connects to their everyday lives. This experiment is focused on an idea that students can use every day at home when making their food or even for safety when using hot liquids.

Guided Inquiry - Pendulums

     The question I decided to focus on for the guided inquiry activity was, which pendulum will come to rest more quickly – a lighter pendulum or a heavier pendulum? The school I currently teach at has invested in CPO science for grades six through twelve, so I had tools outside of the materials given for this activity. To answer the given question I used a stand, pendulum, weights, a timer and a photogate. After setting up the pendulum I set the timer to “count” mode and put ten weights on the pendulum. I pulled the pendulum back until it was at an amplitude of thirty, then released the pendulum and started a stopwatch at the same time. I then repeated the process with five weights. As the pendulum swings through the photogate the timer counts how many times the pendulum passes through the photogate. For my first trial, I set the pendulum up with ten weights and the timer recorded the pendulum passing through the photogate 352 times and stopped after 318 seconds. For my second trial, I set the pendulum with five weights and it passed through the photogate 356 times and stopped after 367 seconds. My data shows that a pendulum with more weight will slow down faster due to air resistance. My results were what I expected because the air resistance opposes the motion of the swinging pendulum so the more weight the pendulum has the stronger the opposing force slows it down.
    
     Overall everything with the experiment went well. My biggest challenge was figuring out how I was going to get from the question to the results that would answer the question.  But, through trial and error I figured out what I needed to do to get the results. To get a different result for this activity I would have students choose to test if the length of the string affects the stop time or the amplitude from which the pendulum is dropped affects the stop time.
    
     I would set the same experiment up for my students because they were already curious and asking questions about the experiment. I would have my students complete the same test, will weight affect the stop time of the pendulum, and then add an extra experiments on how amplitude and the length of the sting affects stop time. This experiment is relevant to my student’s lives because they are always out playing on the swings. After completing the experiment inside with the pendulum, I would take my students outside and see if they get the same results on a swing.
    
     From completing this experiment I would like my students to better understand the concepts we have studied in class. They will get to see how Newton’s Laws and air resistance (friction) affect a pendulum and then later a person on a swing. This experiment will also provide a good teachable moment to introduce the concept of momentum. If and when I do this experiment with my class I feel it will be very successful. It allows students to review past concepts and ideas and test to see how they affect different objects.