Keeping Up the Heat: Insulators (page 2)
Design Your Own Experiment
- How much heat energy is lost through windows? Use three 1-quart (1-liter) jars with lids. Fill the jars half full with hot tap water and secure the lids. Set one jar in a box and fill the box with sand up to the lid of the jar. Leave enough space to remove the jar's lid easily. Place the second jar in a box with sand covering half of the jar. Stand the third jar in a box and do not use any sand to cover it Remove the jars' lids and measure the temperature of the water in the containers. Again, secure the lids on the jars. Again remove the jars' lids and measure the temperature of the water in the containers once every five minutes until the water in the jars reaches the same temperature. Be sure to replace the lid quickly after each temperature reading. You could display a graph of the temperature readings.
- Many windows in buildings and cars are covered with a solar film. What effect does the covering have on controlling the temperature inside a building or car? Repeat the previous experiment replacing the sand insulation with solar film. Check (under glass coating and tinting materials) in your telephone directory for companies that carry solar film.
- Heat reaches the earth by means of radiation. This heat can be reflected. Demonstrate the reflection of radiated heat by replacing two thermometers in a shaded area. Hold a mirror so that the sun's light is reflected onto the bulb of one of the thermometers. Ask a helper to observe the temperature readings on both thermometers.
- Another method of comparing the insulating properties of materials is to observe the rate at which an ice cube melts. Put an ice cube inside a paper cup. Slip a second paper cup inside the first one so that it rests on top of the ice cube. Put an ice cube inside a Styrofoam® cup and, as before, slip a second Styrofoam cup inside the first one (see Figure 30.2). Lift the top cups and observe the ice cubes once every five minutes. Continue until one of the ice cubes completely melts. You could graph and display the results.
- Are thicker cups better insulators? Repeat the previous experiment using a different number of cups. Try four cups with an ice cube between them.
- Some materials conduct or transfer heat better than others. Place the bowls of a wooden, a plastic, and a metal spoon in a 1-pint (500-ml) jar. Use equal-size balls of margarine to secure plastic beads to the handles of the spoons, with all the beads at the same height from the bottom of the jar. Pour about 4 inches (10 cm) of hot water into the jar (see Figure 30.3). As heat is conducted up a spoon, the margarine melts, causing the bead to fall. The faster the bead falls, the faster the heat energy is conducted up the spoon. Rate the conductivity of the materials. You could display the results along with photographs taken during the experiment.
CAUTION: Stop the experiment after one minute or if one thermometer reading nears the highest measurement on the scale.
Get the Facts
- The surface of NASA's space shuttle is covered with special insulating tiles. Obtain information about these special tiles, which help control the temperature inside the spacecraft. Write to NASA, Lyndon B. Johnson Center, Mail Code AP-4, 2101 NASA Road #1, Houston, TX 77058.
- Heat energy is transferred from one place to another by conduction, convection, and radiation. Find out more about these three methods of energy transportation. Use the facts about energy movement to explain how insulation helps to keep a house cooler in the summer and warmer in the winter.
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state’s handbook of Science Safety.