The Heat Is On!

In order to investigate the heat retention ability of water with different heat insulating materials, this experiment measured the temperatuere of a cup of water after thirty minutes of insulation.

The following materials were used:

Paper Towel - chosen for its likely non-insualting ability.

Plastic Wrap - chosen for its ability to lock out air.

Craft Fleece - chosen for its air spaces that make it hard for molecule vibrations to move through as a solid surface would.

Aluminum Foil - chosen for its normal heat encapsulating ability which is used in cooking.

Hypothesis: The craft fleece will be the best insulator due to the varied airy spaces and the plastic wrap will be the least isnulating due to its thin solid structure.

The original temperature of one cup of water when placed in a coffee cup measured at 99.9°C.  After thirty minutes the water temperature was measured and the results were surprising.  The paper towel showed to have let the most heat escape with a resulting temperature of 62.6 °C.  The next least insulating material was actually the craft fleece, with a final of 64.3°C of heat remaining in the cup.  Next with 65.0°C, was aluminum foil, which was not very surprising as it is often used in cooking to trap in heat.  The final item which was unexpected was the plastic wrap, maintaining the highest temperature of water at 65.5°C. 

Tiller, Enger, & Ross (2008) explain that “the best insulator is a vacuum, since there are no molecules to pass on the vibrating motion” (p. 86).  In this case, the plastic wrap sunk down into the cup, forming a vacuum, creating the best insulation and keeping in the most heat.  

In order to do this experiment in the classroom, a few things would need to be changed in order to keep safe experimental procedures in place. For instance I would not use glass cups as they are too likely to get broken.  I also would provide other thermometers that are also not breakable, such as the one I used which is meant for cooking purposes.  This thermometer was digital which also allowed for more accurate measurements.  Another change I would make is to start with water that is at a much lower temperature to protect the students from burns.

I think that students could really get engaged in this experiment if they were able to bring the items in from home to use as insulating materials.  I would be excited to see what they think could be great insulators and to see how they actually work.  I also think students could get into this if the measurements were taken more often, such as every 5 minutes rather than after 30.  If students did this, they could create line graphs of the data which would allow them to work on those necessary graphing skills.

To make this relevant for students and their lives, we could discuss how insulation works in their homes, how it costs their families money when heat escapes.   Also, we could discuss how it may affect their hot chocolate, coffee, or hot apple cider, then share those as a class after the experiment was complete.

In the end I think that with some changes this could be a valuable lesson in the classroom.  And it continues to fight the environmental fight that I so highly value teaching our students about.

ENGAGING IN GUIDED INQUIRY

Unit Question:  What is the effect of large objects colliding with smaller objects?

Method. Move the objects as described in each hypothesis.  Repeat the process three times per scenario.

Question 1: What happens when a small toy car is crashed into a large toy car at rest? 

Hypothesis: When a larger object is at rest and is acted upon by a smaller object, the larger object will move backwards, while the smaller object moves in the opposite direction at a slower velocity.

Results: The small train stopped its forward motion and moved backwards slightly, while the large dump truck moved backwards at a much slower rate than the small train had hit it with. 

Question 2: What happens when a large toy car is crashed into a small toy car at rest?

Hypothesis: When a smaller object is at rest and is acted upon by a larger object, both the larger and smaller objects will continue on in the same direction but at a slower velocity.

Results:  The large dump truck continued to move forward though at a slower velocity, while the small train moved along backwards in front of the large dump truck.

Question 3: What happens when two vehicles, one large and one small, move towards each other at the same velocity?

Hypothesis:  When a large and a small object connect at the same velocity, the two objects will move in opposite directions.

Results: The results varied depending on the velocity of the vehicles. If the vehicles moved at a high velocity towards each other, then the small train moved off to the side and the large dump truck continued forward at a slightly lowered velocity.  If they moved at a slower velocity towards each other, then the small train was moved along with the large dump truck as in question two. 

Observations:

In order to get a different result I would find two objects that have closer mass in order to get less extreme results.

If I were to use this experiment in my class, I would provide students with a large variety of vehicles or objects to choose from.  One option for an extension would be to take two of the same remote control vehicles and add mass to one and see what happens when you crash the two together at the same velocity. I think students would really be engaged by this and if they knew that this was a culminating activity it would get them very involved in the investigation as well.  As I teach teenage students that will one day soon have a license and be driving on the roads, this investigation applies to what they would soon be experiencing and might even make a difference in how they drive, producing safer drivers.

In the end, the students would learn about Newton’s three laws of motion, Momentum and the law of conservation.  And I believe that this investigation would let them have a hands on experience with these scientific concepts, and they would be able to apply them to their lives and to their futures in science.