## Teaching around the nature of energy is supported by 8 vital concepts:

1.1 energy is a quantity that is transferred from device to system. Energy is the capability of a device to perform work. A system has done work-related if it has exerted a force on an additional system over some distance. As soon as this happens, energy is transferred from one device to another. At the very least some that the energy is likewise transformed from one form into an additional during this process. One deserve to keep monitor of just how much energy transfers right into or out of a system.

You are watching: Power is the rate at which energy is transformed. What form of energy is pictured here?The Thunder Dolphin rollercoaster in Tokyo Japan reaches speed of 81 mph. Picture by Ben Garney.  Misconceptions are usual when it comes to understanding forms of energy. ~ above one hand, us all have actually an intuitive feeling of what energy is. But the scientific research behind energy can be complex. Teachers require to find a middle ground in between offering specific explanations, while not oversimplifying or creating further misconceptions.

A common stumbling block is the ide of power and the units to explain energy and power. In the metric system, the devices use to measure energy are Joules. A Joule is the quantity of energy required to advice a 1 kg object to a rate of 2 m/s, or come lift a 1 kg object around 10 cm vertically. Calories, BTUs, and also kilowatt hours are various other units that have the right to be provided to measure up energy.

Power, which is the price of energy transfer, is measured in Joules per second, likewise called Watts. Unlike other units that describe rates (for example, miles every hour for speed, dollars every hour because that wages) the unit "Watt" has actually the "per second" already built in come the unit. There is no the familiar "per second" in the units, students regularly think the a Watt is a quantity that energy, quite than a rate at which power is transferred. For example, a 100 Watt light bulb supplies 100 Joules of electrical energy per second, transforming that mostly right into thermal energy.

Adding come this man is the unit kilowatt hour. A kilowatt hour is 1000 watt times 3600 seconds, or 3.6 million Joules. This is a typical unit of power for electric utilities to use as soon as billing,

A similar and amusing example of the confusion around power and also energy is that electric utilities room often referred to as "power" companies, even though the product they market is energy.

## Bringing these ideas into her classroom

As is depicted in the TED-ed video, simple mathematical principles can be supplied to recognize how energy is quantified, such together measuring power from two different forms, climate converting those amounts into common units. Terms such as power (energy over time), work (force end distance) have the right to be easily measured and calculated. All of these terms have alternate, however related, meanings in daily life, so getting students acquainted with the mathematical definitions will call for students to recognize slightly different interpretations for the exact same words.

Many forms of energy transformation are straight observable in the classroom, for this reason demonstrations room an effective means to illustrate transformations in between different forms of energy. Show instances of class demonstrations illustrating different creates of energy
A chemistry battery running a irradiate bulb the illuminates a surface: chemical energy is reinvented into electric energy, which is revolutionized to radiant and also (mostly) thermal energy. Evaluating the labeling ~ above a light bulb allows students to calculation the performance by detect the ratio of light output (lumens) come power offered (Watts). Higher efficiency light bulbs will certainly produce much more lumens of clearly shows light per Watt.

Hand-crank generator/motors and a irradiate bulb show how kinetic power can be changed into electrical energy. Connecting 2 handheld generator/motors together shows exactly how kinetic have the right to be revolutionized to electric and then earlier to kinetic. A Peltier junction (or thermo electrical generator) transforms electrical energy into a temperature difference, or a temperature distinction into electrical energy. So-called "happy/sad" balls obtainable from science education and learning supply companies show how the elasticity that a material can impact energy transfer. The "happy" ball is made of a polymer that, as soon as compressed, shop elastic potential energy and also releases a similar amount the kinetic energy when it is uncompressed. For example, as soon as the ball is dropped native a elevation of 1 meter, the gravitational potential power is converted to kinetic energy as the ball falls. When the ball impacts the floor, the round compresses and also the kinetic energy is converted right into mostly elastic potential power (and some thermal energy). Once the ball re-bounds, the elastic potential is converted back to largely kinetic power (again, some thermal) causing the sphere to re-bound come a significant fraction the the elevation from which it is released. The ratio of the re-bound height to the release height is the ratio of final energy of the mechanism to the original power -- an estimate of the energy transfer efficiency. The "sad" sphere is make of a polymer the is less elastic. When this ball is compressed, almost all of the mechanical energy is converted to thermal energy and also the round does not re-bound noticeably. Spring toys and also poppers room other instances of similar energy transformations. A dewar or vacuum flask "thermos" is great example of carry of heat energy. Describing exactly how a vacuum flask keeps thermal energy from being moved either in or the end helps college student realize the "coldness" is not a quantity, or a kind of energy, but rather a absence of heat energy. Students may be interested in the story that the development of the vacuum flask and how it to be commercialized through Thermos that benefited indigenous the fact that Dewar did not patent the idea.

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## References

What is Energy? native EIA power Kids, this unit covers energy basics, types of energy, power units and energy calculators.

PhET simulations for to teach Energy, Work and also Power. Interactive simulations that allow students to "experiment" with transforming variables in different energy systems.

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The Physics classroom is an online, free-to-use physics website arisen primarily for high institution physics students and also teachers. Because that example, the animation of energy Transformations for Downhill Skiing illustrates the relationship in between work and energy.