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Projects With Sand & Water Heating Earth's Surface

If you have ever been to the beach on a hot day and tried to walk barefoot across the sand, you've experienced the feeling of the sand getting so hot that your feet feel as though they are burning. In contrast, the water feels nice and cool. Both the water and the sand were exposed to the same sun and the same temperature, but the sand is so much hotter than the water. Learn why different elements of the earth's surface heat at different temperatures.

Specific Heat
- Like all substances, water and sand have different specific heats. The term "specific heat" refers to the amount of heat energy required to raise the temperature of a known quantity of a substance. You can conduct some simple science experiments to learn about the effects of specific heat and the differences in the specific heat of water and sand. To conduct this experiment, you will need two identical desk lamps with 100 watt bulbs, four identical and equal size containers and four identical thermometers. You will also need an equal amount, by volume, of sand and water. Separate the sand and water into equal amounts in two containers of each.
Preparation
- Place all four containers next to each other on a counter. Place the base of the thermometers in the containers at equal depths. Two inches will work fine. Leave the containers on the counter undisturbed, and monitor their temperatures. Continue to check the temperatures until all four containers are the same temperature. While you wait for the containers to reach room temperature, prepare a space to put two of the containers under desk lamps.
Conducting the Experiment
- Once all four containers reach equal temperatures, take one of the containers of water and one of the containers of sand, and place them under the desk lamps. The other two containers will be your controls. Mark the beginning temperature of all of the containers. Allow them to remain under the desk lamps for a period of two hours. Check the temperature of all four containers every 15 minutes and record them. After two hours, turn the desk lamps off. Again, mark the starting temperature, and record the temperature of the containers every 15 minutes for another two hours. Record your data in a log book. Once the two hours has ended, use graph paper and colored pencils to graph your results.
Data Analysis
- Determine which container reached the highest temperature, which container had the lowest temperature, and how quickly the water heated up compared to the sand. You should have observed that the water under the lamp took both longer to warm up and to cool down. The water also should have had a lower temperature over time than the sand because water has a higher specific heat then the sand. In fact, water has a higher specific heat than most substances, which means more energy is required to heat water than to heat other substances. Additionally, water retains heat better than many substances, meaning water takes longer to lose heat it has absorbed.

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