Presentation on theme: "Energy is the ability to do work. It comes in many forms and from many sources. Energy charges your cell phone, cooks your food, lights and heats your."— Presentation transcript:
Energy is the ability to do work. It comes in many forms and from many sources. Energy charges your cell phone, cooks your food, lights and heats your home, and even moves your muscles. Energy comes in many different forms. Where does energy come from, and what happens when you use it? Look Sandy, energy charges my Blackberry!
Energy is never created or destroyed. Energy simply changes from one form to another form. This idea is called the Law of Conservation of Energy. Electrical energy can change into heat energy. Potential energy can change into kinetic energy. Chemical energy can turn into mechanical energy. No energy disappears when these changes happen, but some of the energy turns into energy that you might not use, like heat. When you add it all up, the same amount of energy exists after a change as there was before. It is just in a different form. Suffering succotash! Energy is never created or destroyed, this law is called the Conservation of Energy!
Mechanical energy is the energy an object has because of its motion or position. Energy of motion is kinetic energy. The energy of position is potential energy. Potential energy is energy that an object has stored and can use at another time. Potential energy can change into energy of motion if a force is used to start the object moving. A watermelon resting on the roof of a building has the ability to fall downward, but it will not move until something pushes it. When the watermelon is sitting there, it has potential energy, but no kinetic energy. This watermelon has potential energy
As the watermelon falls, its potential energy changes into energy of motion, or kinetic energy. By the time the watermelon hits the ground, it moves fast because almost all of its potential energy changed into kinetic energy. Right before it hits the ground, it has as much kinetic energy as it can have, and its potential energy is zero, since it is at the level of the ground and cannot fall farther. The watermelon stops moving when it hits the ground. At that time, it hap no potential energy. This is because it has nowhere farther to fall. It also has no kinetic energy because it is not moving anymore. Save the watermelon!
The illustration below shows how the watermelon loses potential energy and gains kinetic energy as it falls. The symbol "J" represents the metric unit of energy, the joule. The joule (J) is the unit for energy!
Chemical energy is the energy stored in the bonds that hold chemical compounds together. When you turn on a flashlight, a set of energy transformations start to take place. The flashlight batteries contain stored chemical energy. When you turn the flashlight on, the chemical energy turns into electrical energy that moves through the circuit inside the flashlight. The electrical energy changes into light energy when it reaches the flashlight's bulb. Some of the electrical energy changes into heat energy too, and-the bulb warms up. No energy is created or lost in this process, it just changes form. Batteries turn chemical energy into electrical energy!
Your alarm clock goes off in the morning. You turn on the light next to your bed. At breakfast, your toast pops up out of the toaster, ready to eat. Each of these events was produced by electrical energy. Electrical energy is produced by moving electrical charges.
All day long, electrical energy changes into other forms of useful energy. Your alarm clock plugs,into the wall. At a particular time, it makes a loud noise. To do this, electrical current flows from the wall socket through the wires of the clock. Electrical current powers the part of the clock that makes sound. This part changes electrical energy into sound energy. That sound energy then travels in waves through the air. Your ear picks up the vibration and then turns that movement into electrical energy inside your brain. Good morning! Electrical energy wakes up your brain!
Turning on your bedside lamp allows electrical energy to move out of the wall socket and through the lamp. As electric current moves through the tiny wire in the light bulb, some energy changes into light energy. Some of the energy also changes into heat energy, which makes the light bulb hot. Be careful some of the electrical energy turns into heat energy!
You can probably predict the energy transformations that happen in your toaster. Electrical energy from the wall socket goes to the heating coils. This energy flowing through the coils changes into heat energy. Heat energy involves the transfer of heat from warmer objects to cooler objects. This heat energy toasts your bread. Some energy also changes into light energy, which you see as an orange glow. At a set time, the toaster uses some of the electrical energy to move a spring inside the toaster. This spring has stored potential energy, so it can move if a force is applied to it. When your bread is toasted, the potential energy of the spring changes into kinetic energy. The spring moves and pushes your toast up from inside the toaster. Many energy transformations occur when you make toast
Solar energy is energy that comes from the Sun. Solar cells mounted on rooftops can convert solar energy into electrical energy. People then use the electrical energy for running appliances, lighting, heating, and cooling. Solar energy can also turn into stored potential energy if it is used to charge special batteries that can then be used at night or on cloudy days. I provide solar power!
Nuclear energy is the energy stored inside atoms, which are the smallest particles that make up all substances. This form of energy is used to produce electricity in nuclear power plants. It is also used to run various kinds of ships, including nuclear-powered submarines. Nuclear energy powers the Sun, as well. Meep, meep! Nuclear energy is stored in atoms!
Describe three energy transformations that occur in your home each day.