Heat Transfer

I decided to use this structured inquiry procedure as a way to settle an argument between my two daughters.  Both of my daughters are involved in a sport, one softball, the other horse riding.  Needless to say, they sometimes fight over their equipment and one such here lately with the cool weather has been their "Under Armor" type shirts.  Of course, one daughter was saying that her sister's shirt kept her warmer so she needed to have it over her sister.  I took both of the shirts and folded them once and placed them over the top of identical mugs that contained 46 degree Celsius water.  I placed a rubber band over the shirt and mug.  I also tested my silicon pot holder and a folded kitchen towel.  I use both when I am removing dishes from the oven, so I was interested in which one would protect my hands better.

At the end of the thirty minutes, I tested all four mugs again.  The mugs that were covered with the shirts were both at 28 degrees Celsius and the hot pad and the kitchen towel mugs were both at 26 degrees Celsius.  I can feel that my hands are equally protected with either the hot pad or the towel.  Maybe I need to get better hot pads?  :)  My daughters will find another reason to fight, because their shirts are equal when it comes to keeping in body heat.

Pendulum

I chose to complete the Pendulum experiment.  I gathered the three washers, a long shoelace, my cell phone to use as a stop watch, pen and paper.  My daughter has a computer desk that is missing a couple of nuts and is turned upside down so it was perfect to use as my stand.  Just like at school, I will use what I have to complete the experiment.  I ran three trials for each of the washers.  I put the washer on the shoe lace and tied it so that it was 70.5 cm from the knot to the bottom of the washer.  I raised the string so that it was parallel to the floor and then released it.  I timed it until it stopped moving.  I ran three trials and averaged the time for each washer.  I also massed out the washers and used the mass to compare the time to.  I had no problems with the experiment (beside my dog chasing it one time).  My average times were 90 seconds for the small washer, 38.3 seconds for medium washer and 24.7 seconds for the large washer.  The thing that surprised me the most was the fact that there was not a linear response of size and time.  I think back to the experiment and wonder if I lifted the string a little higher with the small washer so that there was more potential energy. 

I would have a similar setup for my students with ring stands, three washers and string.  Next school year when I am teaching about potential and kinetic energy, I will use this guided inquiry for my students.  After teaching the curriculum once, I am looking for different experiments for the students to perform and this would be one.  The students would feel like they are using more "scientific" equipment and it would be an easier experiment for the students to complete on their own.  I have had the students complete an similar experiment with rubber bands and rulers.  I would have the students compare this to using a swing and how long would it take to stop depending on how high they went.  The students should come from the lesson with the understanding of how potential and kinetic energy work together and how the different starting heights affect how long the pendulum would swing.