Day 6: [THERMOS EFFICIENCY CHALLENGE!]

Today most of the period was dedicated to the design log section, but we did have other team members work on the thermos. For the "Thermos Efficiency Challenge," we checked how efficient our thermos was, and recorded the temperature to make our heat v.s. time graph. However the recording may need to be done again as the time and temperature when it first entered the thermos was not recorded because of human error. During the testing we made a few minor adjustments along the way as we noticed that the clay on top of the lid was becoming wet and soggy, so we put a small circular layer of foam underneath the clay. We also rechecked that our bottle held the physical requirements of 500 ml just in case, and at the very end of class we started doing the calculations for efficiency.     

Day 4: [BACK TO THE DRAWING BOARD]

Even though the top of the thermos wasn't completed and the thermometer was not in place, we decided to start testing anyways to check the durability of the thermos. The thermos was generally able to retain the heat, but the plastic bottle which we had placed inside the 2L bottle was more than 500 mL, which did not meet the requirements because we needed to use 500 mL or less. Trouble-shooting began as more adjustments are being made and further research was being done. Some of the ideas we shared were, to use a Styrofoam cup or coffee cup for the inside of the 2L bottle as they were both small so would probably use less then 500 ml  Luckily enough a plastic bottle was given to us that met the requirements so we started rebuilding using it right away. Another thing we changed besides the bottle was the sock which was switched to a thicker cotton sock because it's a better insulator as it can trap air from being transferred.

(http://wiki.answers.com/Q/Why_cotton_is_a_good_insulator#page2)

Day 3: [IDEAS PUT INTO ACTION]

We have started constructing our thermos and are adding improvements along the way; another layer of duct tape was added around the steel wool, rice was added in the 2L bottle to insulate the empty spaces, and a wool sock was used to contain the steel wool. We also discovered the aluminum covering would not work, due to the fact that it's too hard, and not flexible which makes it difficult to shape. We have contemplated on what to material to use as the lid, but haven't come up with a conclusion yet. Another adjustment we made to our design is instead of covering the entire 2L bottle in tin foil we decided to add some inside the bottle, but also shape some into small balls to secure the near top of the bottle. This way the foil will apply weight on the rice, and compresses it so it doesn't become loose and fall out. The use of a metal bottle was ditched because we were unable to find the right requirements and later on we found out that metal is not a good insulator but a conductor of heat. As the period reaches its end, our thermos is almost complete, the only thing left to add is the covering for the top and the thermometer. 

http://answers.yahoo.com/question/index?qid=20080210210142AAxsxzk