TO ABSORB OR REFLECT……....

………..THAT IS THE QUESTION

Introduction:

Obviously, solar energy does not stay in the same form as it flows through the Earth system. Energy from the sun enters the Earth system as sunbeams and exits the Earth system as heat. What happens to it in between? (A very good question, my clever student!!) Energy is transferred from one form to another as it flows through the Earth system. For example, energy enters the atmosphere as sunlight. When the sunlight strikes an apple tree leaf the energy is absorbed and some of it is transferred, through photosynthesis, to chemical energy that is stored in the form of sugar. When you eat that apple, some of the energy stored in the sugar is transferred, through cellular respiration, to the kinetic energy that you use to dance all night at the Prom. Dancing, in turn, causes some of your energy to be transferred to heat energy which warms up the gym and eventually flows out of the Earth’s systems into space.

As you know, energy undergoes many changes as it flows through the Earth’s system. In this assignment you will examine how light energy from the sun is converted into heat energy by various materials. Some materials tend to absorb solar energy and convert the solar energy to heat. Other materials are more effective at reflecting solar energy.

Materials:

  • four thermometers if possible.
  • white construction paper

  • four plastic cups

  • colored pencils.

Assignment:

· Cover each cup with a different material-white paper, black construction paper, aluminum foil, and one with no covering.

· Fill each plastic cup two-thirds full of water that is about room temperature.

· Place a thermometer in each cup. (Or margarine, if you don’t have thermometers.)

· Place all four containers in sunlight for sixty minutes.

· Take temperature readings initially and every five minutes. (Or estimate the percentage of margarine that is melted in each cup.)

· Write down your data on a table.

Send me the following. Use complete sentences to answer the questions.

1. Your data table.

2. Make a graph of your data. Plot each container's data on the same graph (temperature vs. time) in a different color.

3. What were the temperature readings for each of the containers when you started?

4. What were the temperature readings for each container at the end of the time?

5. How do the initial readings compare with the final readings?

6. What happened to the energy that arrived in the form of sunlight?

7. What evidence do you have that sunlight was reflected or absorbed?

8. If all of the cups received the same amount of sunlight then how can you explain why they have different temperatures?

9. Predict what will happen to the heat energy that was absorbed by the water in the cups.

Use your knowledge about how energy is absorbed or reflected to answer the following questions.

10. Apply your knowledge about how the various materials reflect and absorb sunlight to common situations. For example, most people living in Africa wear white or light colored clothing because it reflects sunlight and is therefore cooler. Give three examples of HOW various materials are used to absorb or reflect sunlight.

11. Why is it usually cooler in the country than it is in the city?

12. If plants absorb sunlight why don’t they produce a large amount of heat? What energy conversion is taking place in plants?

13. Explain how the transfer of solar energy affects the atmospheric system.

14. Explain how the transfer of solar energy affects the hydrologic system.

15. Explain how the transfer of solar energy affects the geologic system.

16. Explain how the transfer of solar energy affects the biologic system.

GOOD LUCK AND HAVE FUN!!!

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