Energy Project For Science: Graphing Heat Absorption

This project for science in the home or the classroom will allow your child to measure the effect of colour difference on heat absorption in two metal drinking cans. This experiment requires one or preferably two thermometers which should be readily available at the Chemist. The thermometers can be used in a wide range of other experiments are so are a worthy investment.

* two aluminium drink cans (eg, coca cola or pepsi cans)
* two thermometers (one can be used but two gives better results)
* white and black paint + brush
* pencil and paper
* a spreadsheet computer application such as Microsoft Excel

Procedure:

Step 1: Paint one can white and the other black, including the top of the can. Leave them until the paint is dry.

Step 2: Fill both cans with tap water until they are about 1 cm (half an inch) from the top. Place a thermometer into each can.

Step 3: After about 30 seconds, record the temperature of both cans as time zero. Then place both cans in the sun and record the temperature every 15 minutes. The following table would be suitable:

What Will Happen?

Your child will have two sets of temperature results. The black can will have absorbed more heat than the white one and so the temperature in that can should rise more quickly than in the white can. To see these data as graphs she will need to use a spreadsheet program.

Enter the data into the spreadsheet exactly as it is in the table. Note that the cells with the temperatures must have NUMBERS ONLY; no letters at all. In Microsoft Excel, once you have highlighted the data, select the graphing function. To get the graphs of temperature change select the X-Y SCATTER option, and have the dots joined. Then just click finish and you are done.

Possible Extensions:

This project for science can be extended by using more cans of different colours. This does require the additional materials to prepare the cans, but the comparison of the different data sets on the spreadsheet and accompanying graphs will be rewarding for your child.

If you are considering doing this experiment with many different coloured cans and cannot collect data from all the colours at once, it would be best to do this experiment inside under a hot lamp such as a high wattage incandescent bulb set close to the cans.

This will reduce the effect of outdoor conditions on the temperatures from the can and is a good way to get your child thinking about good experimental design.