What is Energy?

Vimeo ID: 75222935

This video defines energy and explores some of its most common forms. It can be used as a supplement to an investigation, or may stand on its own to introduce a lesson or extend student learning.


Video Transcript

What is energy? Most of probably understand the concept of energy, or at least we can recognize it when we see it.

Here are some basic concepts that will help us define energy.  First, energy is required to make things change. For example, to change this No. 2 pencil from one useful writing utensil into two less useful pieces, we need to use energy.

Energy is the ability to do work. But we're not talking about going to work or doing your chores, we're talking about work as defined in the physical sciences. Work is the application of a force to move an object in the direction of the force. Like, when you pedal a bicycle, or when an electric motor lifts an elevator. Energy is conserved. So, what does that mean? It means that one form of energy may be transformed into another form, but the total amount of energy remains the same. In other words, energy cannot be created, nor can it be destroyed.

One of the easiest ways to recognize energy is to know the different forms it can take. All energy falls into two categories: potential and kinetic energy. Potential energy depends on the position of an object or the arrangemet of its constituent parts. Kinetic energy is the energy of motion. Think about the energy of a brick resting on your foot compared to a brick being dropped on your foot. The moving brick has more kinetic energy, which you become painfully aware of when it transfers some of that energy onto your foot. When both bricks are resting on your foot, they have the same potential energy.

There are four main types of potential energy. First, we have chemical energy. Chemical bonds holds atoms together. It takes energy to break these bonds and to move atoms further apart. Energy is released when new bonds form and atoms come closer together. Chemical energy is where the energy in our food comes from. Our body digests food, like this sandwich, and uses the energy to do things.

Another type of potential energy is mechanical energy. Mechanical energy is stored in a device by the application of a force, like the stored energy in a pulled bowstring. Once it is released, stored energy is converted into kinetic energy.

Two other types of potential energy include nuclear energy and gravitational energy. Gravitational energy is related to an object's position in a gravitational field. This tennis ball has a higher potential energy up here than when it falls to earth.

OK, enough about potential energy. Let's talk about kinetic energy. First of all, there's hydro or wind energy. All objects in motion have kinetic energy that can be transferred to other objects by collisions.  For example, the movement of air can turn windmills to pump water or produce electricity.

Speaking of electricity, there's also electrical energy. Electrical energy is the energy associated with the movement of ions and electrons. When electrons flow through wires, we call it electricity. In addition, there's radiant energy, which comes from light waves, x-rays, and microwaves, and it's all around us.

And then, there's thermal energy. Thermal energy is the energy that results from the movement of atoms and molecules and is related to their temperature.  The faster the particles move, the greater the amount of energy, and the higher the temperature.

Sound energy is produced by the periodic movement of matter in a medium. Sound can travel through gases, solids, and liquids.  Pretty much any matter, but not through the vacuum of space, because there's no matter there. So you know that old sci-fi movie line about how "in space, no one can hear you scream"? Totally true.  And a little terrifying.

So there you have it, the main types of potential and kinetic energy. All this talk about energy makes me want to absorb some.

Is that my sandwich?!

Uhh ... potentially ...

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