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

1.1 power is a quantity that is transferred from mechanism to system. Power is the capacity of a device to perform work. A system has actually done work if it has exerted a force on an additional system over some distance. Once this happens, energy is transferred from one mechanism to another. At the very least some the the power is additionally transformed native one kind into one more during this process. One deserve to keep monitor of just how much energy transfers into or out of a system.

You are watching: The rate at which energy is transferred is called


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What kind of energy is pictured here?The Thunder Dolphin rollercoaster in Tokyo Japan reaches speed of 81 mph. Photo by Ben Garney.
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Misconceptions are usual when it pertains to understanding creates of energy. On one hand, us all have actually an intuitive feeling of what power is. Yet the science behind power can be complex. Teachers need to discover a center ground in between offering specific explanations, while no oversimplifying or producing further misconceptions.

A common stumbling block is the ide of power and the systems to describe energy and also power. In the metric system, the systems use to measure power are Joules. A Joule is the lot of energy required to accelerate 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 kilowatt hrs are various other units that have the right to be offered to measure up energy.

Power, i beg your pardon is the price of power transfer, is measure in Joules every second, likewise called Watts. Unlike various other units that describe rates (for example, miles per hour because that speed, dollars per 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 often think that a Watt is a quantity the energy, quite than a rate at which energy is transferred. For example, a 100 Watt light bulb provides 100 Joules of electrical energy every second, transforming it mostly right into thermal energy.

Adding to this man is the unit kilowatt hour. A kilowatt hour is 1000 watt times 3600 seconds, or 3.6 million Joules. This is a usual unit of power for electrical utilities to use when billing,

A similar and amusing example of the confusion around power and also energy is that electrical utilities room often called "power" companies, even though the product they sell is energy.

Bringing these ideas into your classroom


As is shown in the TED-ed video, straightforward mathematical concepts can be offered to understand how power is quantified, such as measuring energy from two different forms, climate converting those quantities into usual units. Terms together as strength (energy over time), job-related (force end distance) can be conveniently measured and calculated. All of these terms have alternate, however related, meanings in day-to-day life, so obtaining students acquainted with the mathematical interpretations will need students to know slightly different definitions for the same words.

Many develops of energy revolution are directly observable in the classroom, so demonstrations room an effective way to illustrate transformations in between different creates of energy.

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Show instances of class demonstrations showing different forms of energy
A chemical battery running a irradiate bulb the illuminates a surface: chemical power is reinvented into electric energy, i m sorry is changed to radiant and (mostly) heat energy. Analyzing the labeling on a irradiate bulb enables students to calculate the efficiency by detect the proportion of light output (lumens) come power supplied (Watts). Greater efficiency light bulbs will produce much more lumens of clearly shows light every Watt.

Hand-crank generator/motors and a irradiate bulb show how kinetic power can be revolutionized into electric energy. Connecting 2 handheld generator/motors with each other shows how kinetic can be reinvented to electric and then back to kinetic. A Peltier junction (or thermo electric generator) transforms electric energy into a temperature difference, or a temperature distinction into electrical energy. So-called "happy/sad" balls accessible from science education and learning supply companies show how the elasticity of a material can impact energy transfer. The "happy" sphere is make of a polymer that, when compressed, shop elastic potential energy and also releases a similar amount the kinetic energy when that is uncompressed. Because that example, when the sphere is dropped from a elevation of 1 meter, the gravitational potential power is converted to kinetic energy as the ball falls. As soon as the ball effects the floor, the ball compresses and also the kinetic power is converted into mostly elastic potential energy (and some thermal energy). When the ball re-bounds, the elastic potential is converted ago to mainly kinetic energy (again, part thermal) resulting in the sphere to re-bound to a far-reaching fraction the the height from which it is released. The ratio of the re-bound height to the release height is the proportion of final power of the device to the original energy -- an calculation of the power transfer efficiency. The "sad" round is do of a polymer that is much less elastic. As soon as this sphere is compressed, almost every one of the mechanical power is converted to thermal energy and also the round does not re-bound noticeably. Spring toys and also poppers space other instances of similar energy transformations. A dewar or vacuum flask "thermos" is terrific example of deliver of thermal energy. Describing how a vacuum flask keeps thermal energy from being moved either in or the end helps student realize that "coldness" is not a quantity, or a form of energy, but rather a lack of thermal energy. Students might be interested in the story that the advancement of the vacuum flask and also how it to be commercialized by Thermos that benefited from the fact that Dewar did not patent the idea.

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References

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

PhET simulations for to teach Energy, Work and Power. Interaction simulations that enable students to "experiment" with transforming variables in various energy systems.

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