Changing Forms of Energy

* How energy makes everyday activities possible

* Identify Potential and Kinetic energy

Energy makes change possible. Energy moves cars along the road and boats through the water. Energy bakes a cake in the oven, keeps ice frozen in the freezer, and lights homes.

Scientists define energy as the ability to do work. Modern civilization is possible because people have learned how to change energy from one form to another and then use it to do work.

Just like there are different forms of electricity, there are different types of energy too. The two main types of energy are:

• Kinetic Energy
• Potential Energy

What is potential energy?

Potential energy is the stored energy an object has because of its position or state. A bicycle on top of a hill, a book held over your head, and a stretched spring all have potential energy.

How to Measure Potential Energy

The standard unit for measuring potential energy is the joule, which is abbreviated as "J."

How is it different from kinetic energy?

Potential energy is stored energy while kinetic energy is the energy of motion. When potential energy is used it is converted into kinetic energy. You can think of potential energy as kinetic energy waiting to happen.

If an object is moving, it is said to have kinetic energy (KE).Potential energy (PE) is energy that is "stored" because of the position and/or arrangement of the object. The classic example of potential energy is to pick up a brick. When it's on the ground, the brick had a certain amount of energy. When you pick it up, you apply force and lift the object. You did work. That work added energy to the brick. Once the brick is in a higher/new position, we would say that the increased energy was stored in the brick as PE. Now the brick can do something it couldn't do before; it can fall. And in falling, can exert forces and do work on other objects.

Click Here to learn more about Potential and Kinetic energy. Be sure to note at least 2 things you learn from the video to share with your classmates.

This law states that energy is never created or destroyed, it is only changed from one state to another. One example is the chemical energy in food that we turn into kinetic energy when we move.

Energy can take a number of different forms. Here are some examples:

• Chemical - Chemical energy comes from atoms and molecules and how they interact.
• Electrical - Electrical energy is generated by the movement of electrons.
• Gravitational - Large objects such as the Earth and the Sun create gravity and gravitational energy.
• Heat - Heat energy is also called thermal energy. It comes from molecules of different temperatures interacting.
• Light - Light is called radiant energy. The Earth gets a lot of its energy from the light of the Sun.
• Motion - Anything that is moving has energy. This is also called kinetic energy.
• Nuclear - Huge amounts of nuclear energy can be generated by splitting atoms.
• Potential - Potential energy is energy that is stored. One example of this is a spring that is pressed all the way down. Another example is a book sitting high on a shelf.

click here to learn about sound energy

Click here to learn more about sound

Light is a type of energy known as electromagnetic radiation. It is given out by hot objects such as the Sun, light bulbs, and LASERS. When light hits a surface, its energy can be absorbed (soaked up), REFLECTED, or deflected by REFRACTION.

WHAT IS LIGHT?

Light is made up of little packets of energy called photons. Most of these photons are produced when the atoms in an object heat up. Heat “excites” the electrons inside the atoms and they gain extra energy. This extra energy is then released as a photon. The hotter an object gets, the more photons it gives out.

HOW DOES LIGHT TRAVEL?

Light travels as a wave. But unlike sound waves or water waves, it does not need any matter or material to carry its energy along. This means that light can travel through a vacuum—a completely airless space. (Sound, on the other hand, must travel through a solid, a liquid, or a gas.) Nothing travels faster than light energy. It speeds through the vacuum of space at 186,400 miles (300,000 km) per second.

WHAT ARE SHADOWS?

Light waves travel out from their source in straight lines called rays. Rays do not curve around corners, so when they hit an opaque object (one that does not allow light to pass through it), they are blocked from reaching the other side of that object. We see a dark shadow in the area from which light is blocked.

WHAT MAKES SOME MATERIALS OPAQUE?

When light falls on a material, the energy in its photons can affect the atoms in the material. In some materials, such as metal, the atoms absorb some of the photons so light does not pass through them. These materials are opaque. In other materials, such as glass, the atoms cannot absorb the photons and light passes through them. These materials are transparent.

REFLECTION

Light rays reflect (bounce) off objects. The Moon shines because it reflects light from the Sun. Smooth surfaces, such as mirrors, reflect light in one direction.

WHAT HAPPENS WHEN YOU LOOK IN A MIRROR?

At first sight, your image is identical to you. But a closer look shows that as you lift your right hand, your image raises its left. Reflection always flips an image from left to right. If you hold up a sheet of paper with writing on it, the image in the mirror shows the writing in reverse.

REFRACTION

Light travels more slowly through some materials than others. The change in speed can cause light rays to change direction. This directional change is called refraction.

WHY IS A SWIMMING POOL DEEPER THAN IT LOOKS?

Refraction can make things look closer than they really are. The difference in speed between light traveling through water and through air means that, from the surface, a 13-ft (4-m) pool appears to be just 10 ft (3 m) deep. Glass is another material that refracts light. It is used to make eyeglasses and other lenses.

LASER

A laser produces an incredibly powerful, concentrated form of light. Inside a laser, light waves are bounced back and forth between two mirrors to build up energy before being released as a narrow beam.

WHY IS LASER LIGHT SO SPECIAL?

Laser light does not spread out in the way that light from other sources does. All the light waves in laser light are precisely in step with each other. As a result, laser light can be concentrated and controlled far more accurately. It can carry television and other signals over great distances without losing quality.

Learn more about Light Energy with science kids. Click here

Click here to learn more about concave and convex lenses.

Chemical Energy is energy stored in the bonds of chemical compounds (atoms and molecules). It is released in a chemical reaction, often producing heat as a by product (exothermic reaction). Batteries, biomass, petroleum, natural gas, and coal are examples of stored chemical energy. Usually, once chemical energy is released from a substance, that substance is transformed into an entirely new substance.

For example, when an explosive goes off, chemical energy stored in it is transferred to the surroundings as thermal energy, sound energy and kinetic energy.

Let's see one good example in the fire-place illustration below.

The dry wood is a store of chemical energy. As it burns in the fireplace, chemical energy is released and converted to thermal energy (heat) and light energy. Notice that the wood now turns into ashes (a new substance)

Food is also a good example of stored chemical energy. This energy is released during digestion. Molecules in our food are broken down into smaller pieces. As the bonds between these atoms loosen or break, a chemical reaction will occur, and new compounds are created. When the bonds break or loosen, oxidation occurs almost instantly.

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• In 2008 about 7% of the energy used in the United States was from renewable sources.
• A modern windmill or turbine can generate enough electricity to power around 300 homes.
• People have used waterpower to grind grain for over 2,000 years.
• Geothermal power uses energy from geysers, hot springs, and volcanoes.
• The entire world could be powered for a year from the energy from the sun that falls on the Earth's surface in one hour. We just need to figure out how to harness it!

Click here to see what you know about energy!