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Road to Saving Energy 1.Streamlining the shape of HEVs is important to their efficiency. Discuss with students how when a hand is placed outside a moving car’s window the wind slips over the hand held parallel to the road, but when the hand is held vertically, the wind buffets and pushes the hand. The same is true for the shape of a car. To demonstrate, use two identical model or toy cars. Tape a piece of cardboard at a right angle to the front or back hood or top of one car. Put both cars on an inclined track and release to see which makes it to the bottom first. Or use an electric fan to conduct a simple “wind tunnel” experiment with the two cars, one with the cardboard “sail” and one without to see which is pushed back by the air. 2.A
reverse experiment also can be tried. Use two identical model cars–try to find ones
with a “blocky” or square body–and have the students design and attach
streamlining shapes, such as a tapered nose or a tapering rear fin, and try the wind
tunnel or race track tests. Have students chart the differences. 3.Since
weight is also a variable, conduct an experiment with weighted cars. If possible, use two
identical, battery-powered toy radio-controlled cars. Using fresh batteries for power
(preferably from the same pack for test control) attach some weights to one car (enough
small metal pieces, for example, to make a difference in their weights). Weigh both cars
and then “drive” them until the batteries fail. Chart to see if the heavier car
runs out of power faster. This experiment may require part of several class periods, so
students will need to keep good records. Black
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Last Updated: 02/16/03 |
