FRAMING PATHWAYS TO ANSWERS: THE SCIENTIFIC PROCESS IN ACTION STAYING COOL
Cooling with Sunshades
Grade Level: 9-12
Duration: Two to Three - 45 minute periods
In this lesson, students discuss some of the basic properties of temperature and heat, and learn different ways in which heat can affect substances. As an example, the students consider sunlight and how it can heat up objects on Earth. They construct a simple device based on the phase change of water from ice to liquid to investigate the effectiveness of different shading materials, as well as the cost-effectiveness of different shade designs. They discuss how the MESSENGER spacecaft uses a sunshade to keep comfortable at Mercury’s distance from the Sun.
How can passive cooling methods keep an object at a comfortable temperature?
Radiation from the Sun is the main source of energy on Earth. It heats the Earth to a temperature at which life is sustainable.
Temperature describes the average internal energy of the atoms and molecules of which the substance is composed; it is also a measure of the amount of disorder in the substance.
Heat can be transmitted via conduction, convection, and radiation.
Heat interacting with material causes it to change temperature, size, or physical state (phase).
When a substance changes phase, its temperature remains the same until all of it has changed its phase; the temperature of ice water can rise only after all the ice has melted.
When designing a scientific experiment, it is important to consider possible sources of errors and improve the basic design to reduce these errors.
In designing devices to be used in practical applications, it is important to take into consideration the cost-effectiveness of the device: the efficiency of the device in solving the problem compared with its total cost.
MESSENGER Mission Connection
MESSENGER uses passive cooling methods such as a sunshade to make sure the spacecraft components can operate in safe temperatures.
Standards & Benchmarks
NATIONAL SCIENCE EDUCATION STANDARDS
Standard B5: Conservation of energy and increase in disorder
- Heat consists of random motion and the vibrations of atoms, molecules, and ions. The higher the temperature, the greater the atomic or molecular motion.
- Everything tends to become less organized and less orderly over time. Thus, in all energy transfers, the overall effect is that the energy is spread out uniformly. Examples are the transfer of energy from hotter to cooler objects by conduction, radiation, or convection and the warming of our surroundings when we burn fuels.
Standard E1: Abilities of technological design
- Identify a problem or design an opportunity: Students should be able to identify new problems or needs and to change and improve current technological designs.
- Propose designs and choose between alternative solutions: Students should demonstrate thoughtful planning for a piece of technology or technique. Students should be introduced to the roles of models and simulations in these processes.
Standard F6: Science and technology in local, national, and global challenges
- Individuals and society must decide on proposals involving new research and the introduction of new technologies into society. Decisions involve assessment of alternatives, risks, costs, and benefits and consideration of who benefits and who suffers, who pays and gains, and what the risks are and who bears them. Students should understand the appropriateness and value of basic questions�"What can happen?"�"What are the odds?"�and "How do scientists and engineers know what will happen?"
BENCHMARKS FOR SCIENTIFIC LITERACY (AAAS PROJECT 2061)
- Whenever the amount of energy in one place or form diminishes, the amount in other places or forms increases by the same amount.
- Heat energy in a material consists of the disordered motions of its atoms or molecules. In any interactions of atoms or molecules, the statistical odds are that they will end up with less order than they began�that is, with the heat energy spread out more evenly. With huge numbers of atoms and molecules, the greater disorder is almost certain.
- Scientific research identifies new materials and new uses of known materials.