 use of heat and turbines to actuate electrical generators should be emphasized. This can also be a research activity as a preamble to the design activity. Students can identify the kind of fuel and generation system being used in their community, perhaps organizaing a field trip to the power generation plant.
The following are points to cover during the introductory discussion:
- Gases and their properties (air in particular)
- The nature of electricity and electrical generators
- A brief discussion of fossil fuels, their depletion and how they impact the natural environment
- Alternative fuel sources (wind in particular)
- Wind turbines, their design, and how they function. You can share the following Wind Turbine Animation with students as a way to frame this part of the discussion:
Wind Turbine Animation
- The fact that wind turbines can transfer mechanical energy into electrical energy. You can have students compare/contrast steam generated by a fossil fuel boiler and wind as energy source. (NOTE: The students will conduct experiments to find out HOW this transfer takes place.)
Discussion Following Procedure Part 2: The Competition Round 1: What Effect Does Temperature and Pressure Have On Gases?
After part 2 of the procedure (below), start a new discussion in which the students are asked to consider the behavior of air (which is a gas) and how wind is formed. Ask students what affects gases and their movement. After a few responses, discuss how temperature and pressure affect how gases behave.
Refer to the attached document (What Effect Does Temperature Have On Gases?) for a demo and in-class experiment that can be used to further the discussion.
Consider what happens to warm air as it rises. When a gas is warmed, the molecules comprising the gas are not as closely packed together. As temperature decreases, however, the molecules come closer together. This closeness of molecules reflects the density of the gas as given by the equation:
Density = Mass/Volume
Thus, as the volume increases, the density decreases and vice-versa.
The effects of temperature and pressure can be combined and be described by the following equation.
PV = nRT where:
P = Pressure
V = Volume
n = a given number of air molecules
R = Ideal gas constant 8.3145 J/ (K mol)
T = Temperature
P(M/D) = nRT where:
M/D is Mass/Density and is substituted mathematically for volume.
Ideally, you can work in partnership with their math teacher to have the students work on some sample calculations before they do this experiment. This will make the connection more salient
Given that the students now have a familiarity with air and how it is affected by temperature and pressure, ask them how they think wind forms. Wind is formed when air moves from one place to another due to differences in temperature and pressure. Other things can affect this movement as well. Ask the students what they think could affect wind movement and what affects wind can have on different areas of the earth (e.g., continents and oceans). Some examples of things that affect wind movement include landscapes (e.g., mountains act as an obstacle), climate, other wind parcels (fronts) and the earth’s rotation.