Heat Transfer Guided Inquiry

Cups, with "HOT" water.

This week I conducted an experiment to find out which material would insulate the mug of hot water the best.  I decided to use tin foil, wax paper, plastic wrap and a t-shirt.  The first three were materials I use in the kitchen and wanted to see which worked best for keeping something warm.  I decided on the t-shirt just because I thought it would be interesting to see it's heat retention properties and we use it for clothing to stay warm.  After putting hot water in identical mugs and then covering the mugs with the 4 materials as lids, I waited 30 minutes to then measure the temperature of the water inside.  I then compared my before and after temperatures and determined the temperature changes.  I ran three trials of my experiment before I was comfortable with my data's results.  I wanted to verify my findings were right because my first trial produced interesting results.

Materials Used

Predictions and data from first two trials.

The t-shirt actually was the best in 2 of the 3 trials and had the best average temperature loss.  It kept the water the hottest out of the 4 materials.  I was very shocked because I thought it would be the worst of the all.  After reading about heat transfer, I realized the reason the t-shirt worked the best because it had lots of spaces.  Space is a poor conductor of heat because it increases the space that the molecules have to move to transfer the heat.  It had lots of space and therefore was a poor conductor of heat, and trapped more heat inside than it let out. 

Trial three's data and average temperature change chart

Out of the 3 kitchen materials, the tin foil, plastic wrap and wax paper, the tin foil was best, followed by the wax paper and lastly the plastic wrap.  The tin foil was much better than the other two.  The wax out performed the plastic which was interesting to me.  The picture above shows the third trial's data plus the average temperature change chart. 





I would like to run this experiment with liquids of different densities.  I think if I used a thick gravy the results might have been different.  Because the gravy is denser than the water, it would probably retain heat on its own better, and then the covers might not play as large of a role as they did in the water experiment.  I would even try other materials like a hamburger or pasta.  Again, maybe the density of the object would affect the outcomes.

Pendulum Experiment

 The question I decided to investigate this week was “Which pendulum will come to rest more quickly- a lighter pendulum or heavier pendulum?”  To investigate this question I set up two pendulums of equal length (15 inches) but with different sized washers.  One pendulum had a washer weighing 28 grams, the other had a washer weighing 2.8 grams.  After conducting a few trials, my results were exactly what I had predicted to happen, the lighter one came to rest sooner than the heavier one.  This was a pretty easy experiment to conduct, there were not too many things that could go wrong.  I had a few issues at first trying to get the pendulum to swing without hitting into the desk it was hanging from, but after a few trials, I was able to get it to swing in a semi-strait path without any contact with the desk. 

Materials needed for the experiment, minus the vitamin water.

Some things that I could change to this experiment to get a different or modified result would be to change the question to “Does the length of the pendulum affect the time it will take for a pendulum to come to a rest?”  This would change the variable tested during the experiment from testing the weight to testing the length of the strings used.  I’m sure that with different variables would come different results. 

This experiment could easily be modified as a lesson for my 5^th grade class.  I could change the wording around to make it more engaging for my students.  Instead of using the word pendulums, which I would then introduce to them after they conducted the experiments, I could call it a swing experiment.  I would pose the question as “Does the weight of the person affect how long they will swing without being pushed?”   We could then use the swings on the playground to test out their hypothesis.  I think by changing some vocabulary and making it relevant to something they use in their free time during recess would make it more engaging for my students.  Also the fact that we would be using swings on the playground would increase the fun and interest level among my class.  I think that this would be a great way to teach the children about the affects mass plays in momentum of objects, much like the pendulum experiment taught me.