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Introduction: Demonstration of Potential Energy
Ask the class to watch closely, and tell them that you will ask them to describe what happens in terms of energy. Remind students that energy is never created or lost; it is just transferred between objects. Hold up a rubber ball so that the class can see it, and drop it. It should bounce several times before stopping. As a class, discuss where the ball got the energy to move.
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Explaining Potential Energy
Explain to the class that there are two types of energy: energy of motion and energy of position. Write the words “kinetic energy” and “potential energy” on the board and explain that we call energy of motion “kinetic energy” and energy of position “potential energy.” Prompt students to explain that the ball had a lot of potential energy when you held it up high, but that the potential energy turned to kinetic energy when you dropped it.
As an important side point, discuss the fact that the ball bounced less and less each time. This is because of friction and air pressure, both of which cause the ball to lose energy as it bounces. If it weren’t for friction and air pressure, the ball would bounce to the same height as it was at originally.
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Roller Coaster Activity
Roller coaster physics is the perfect potential energy example. Tell students that they will work in groups to design a roller coaster with two drops and a loop, but no mechanical gears to pull the car along. Explain that students should decide the height and location of each of the drops, as well as whether the distance between them should be small or large. Circulate among the groups redirecting the discussion as needed and answering questions. Encourage students to draw a diagram of their completed roller coaster.
When the groups have come to their conclusions, have them share their roller coasters with the class, making sure that they discuss their results in terms of potential energy and kinetic energy. Students should have come to the following conclusions:
· The roller coaster should start at the top of the first drop so that it will begin with potential energy.
· The first drop should be considerably higher than the other drop and the loop, because some of that potential energy will be lost.
· The second drop should be higher than the loop if it comes first, and the loop should be higher than the second drop if it comes first.
· The distance between each drop should be small so that very little energy is lost to friction and air pressure.
Encourage students to research roller coaster physics and potential energy in their free time, and send them to an online site to build a virtual roller coaster, if time allows. Use this potential energy example to spark their interest in physics in general and energy in particular.