Vocabulary+CH15


 * energy : ** is the ability to do work. In other words, energy is transferred by a force moving an object through a distance. Work is a transfer of energy. Both work and energy are typically measured in joules (J). Recall that 1 joule equals 1 newton-meter, the work done when an object is moved 1 meter by a 1-newton force. Although energy can take many different forms, it can always be measured in joules.

** The kinetic energy of any moving object depends upon its mass and speed. To calculate the kinetic energy of an object in joules, multiply ½ by the object's mass (//m//) in kilograms and the square of its speed (//v//) in meters per second.
 * kinetic energy


 * potential energy **is energy that is stored as a result of position or shape.

Example of Potential and Kinetic Energy media type="google" key="-5211209985372994776&hl=en" width="400" height="326" ** When you lift your gym bag up to the top seat of the bleachers, you do work to increase the potential energy of your bag. Potential energy that depends upon an object's height is called **gravitational potential energy**. This type of potential energy increases when an object is raised to a higher level.
 * gravitational potential energy **



**The potential energy of an object that is stretched or compressed is known as ** elastic potential energy **. Something is said to be elastic if it springs back to its original shape after it is stretched or compressed. Think back to the last time you stretched a rubber band between your fingers. By stretching the rubber band, you did work on it. [|For FUN CLICK HERE!] ** The energy associated with the motion and position of everyday objects is **mechanical energy**. Don't be confused by the name, however. Mechanical energy is not limited to machines. Mechanical energy is the sum of an object's potential energy and kinetic energy. Speeding trains, bouncing balls, and sprinting athletes all have mechanical energy.
 * elastic potential energy
 * mechanical energy **

**Almost all of the matter around you contains atoms. These particles are always in random motion and thus have kinetic energy. The total potential and kinetic energy of all the microscopic particles in an object make up its ** thermal energy **. When an object's atoms move faster, its thermal energy increases and the object becomes warmer.
 * thermal energy

media type="google" key="-8664457030949541742&hl=en" width="400" height="326" ** **The campers in Figure 7 are toasting marshmallows over a campfire. The source of energy for the fire is the energy stored in wood. When the wood is burned, energy is released and heats the marshmallows as well as the area around the campfire. The energy stored in wood is chemical energy. ** Chemical energy ** is the energy stored in chemical bonds. When bonds are broken, the released energy can do work. All chemical compounds, including fuels such as coal and gasoline, store energy.
 * SOLAR/THERMAL ENERGY
 * chemical energy


 * FIGURE 7

electrical energy **Many devices you use every day use electricity, or electrical energy. ** Electrical energy ** is the energy associated with electric charges. Electric charges can exert forces that do work. Batteries, which convert chemical energy to electrical energy, are used to operate portable CD players, flashlights, and calculators. Electrical energy also occurs in nature. The powerful bolts of lightning shown in Figure 8A are produced by electrical energy. **Figure 8** Two major forms of energy are electrical energy and electromagnetic energy. **A** Lightning bolts transfer electric charge. **B** Galaxies are giant structures in space that typically contain billions of stars. The stars give off enormous amounts of electromagnetic energy. electromagnetic energy **he sun radiates electromagnetic energy into space and is the source, either directly or indirectly, of most of the world's energy supplies. ** Electromagnetic energy ** is a form of energy that travels through space in the form of waves. Visible light and X-rays are examples of electromagnetic energy. Because electromagnetic waves can travel long distances through air and space, they are often used for communication. The glowing galaxy in Figure 8B is emitting electromagnetic energy of many kinds.

** The nucleus of an atom is held together by strong and weak nuclear forces, which can store an enormous amount of potential energy. The energy stored in atomic nuclei is known as ** nuclear energy **. A nuclear power plant uses nuclear fission reactions to generate electricity. Nuclear fission is a process that releases energy by splitting nuclei apart.
 * nuclear energy