Guide #2 Forms of Energy

Mechanical Energy detonates, chemical energy stored in it is Mechanical Energy is the energy an object transferred to the surroundings as possesses due to its motion or position. For thermal energy, sound energy and example, a thrown baseball is in motion. On kinetic energy. When this happens, the atoms the other hand, a brick held in your hand has in the firework are rearranged and become new stored mechanical energy that would turn into substances. motion if you dropped it. So, mechanical energy is both potential and kinetic energy.

Examples of mechanical energy: Because so many objects are in motion (or could be in motion), there are literally billions of examples. Electric motors, jet engines, car engines, and windmills are examples of kinetic mechanical energy used by humans. Objects in nature that 1 2 3 are in motion, and therefore have kinetic mechanical energy, include wind, tides, and Chemical energy is stored in the bonds between atoms. waves. Wood stores chemical energy in the bonds Chemical energy between its atoms. As it burns, the atoms are Chemical Energy is energy stored in the bonds rearranged to form new chemicals. Chemical between atoms. Batteries, gasoline, coal, and energy is released and converted to thermal sugar have stored chemical energy that people energy (heat) and light energy. Then the wood can use. Since it is stored, it is a form of turns into ash, water, and gases (new potential energy. substances).

Chemical reactions involve rearranging atoms. Electrical energy Usually, once chemical energy is released from Electrons are tiny particles that orbit the a substance, that substance is transformed into nucleus of an atom. Humans can force an entirely new substance. For example, when electrons along a path from one place to the vinegar reacts with baking soda, they turn into other. For example, in a copper electrical wire sodium acetate, water, and carbon dioxide. electrons are forced from one copper atom to the next, and so on. Electrical energy is energy Chemical reactions that produce heat are called from moving electrons. Since the electrons are exothermic reactions. Exothermic reactions moving, electrical energy is a form of kinetic make their surroundings warmer by transferring energy. heat. Chemical reactions that absorb heat are called endothermic reactions. An endothermic There are special materials, called conductors, reaction makes the surroundings cooler by that allow electrons to flow through them. absorbing heat from them. Copper and aluminum are good conductors. Some materials do not allow electrons to flow Examples of chemical energy: The chemicals in easily through them, and they are called fireworks store chemical energy in the bonds insulators. Glass and rubber are good between their atoms. When a firework insulators.

Adapted from: Forms of Energy, US Energy Information Administration, 2014. An electrical current occurs when electrons are because it is so much larger than a cup of pushed, sort of like the current of a stream coffee. Therefore, temperature is simply how pushes a floating stick. The current forces hot or cold an object is, measured in degrees. electrons to move through a wire until they Heat is the transfer of thermal energy from one reach an electrical appliance like a light bulb. object to another.

Examples of thermal energy: Heat always flows from hotter objects to cooler ones. If you hold a warm penny, thermal energy will flow from the penny to your hand. The atoms in the penny would start to vibrate more slowly, and the atoms in your skin would start to vibrate more quickly. Thermal energy would continue to flow from then penny to your hand until both your hand and the penny were the same Electrical current "pushes" electrons from atom to atom in a temperature. copper wire Thermal energy flows from a light bulb to the Examples of electrical energy: Electrical energy air in the room. When the light bulb is turned is formed when chemical energy from a battery off, the thermal energy continues to flow until is used to push electrons along a copper wire. the light bulb is the same temperature as the When the electrical energy reaches a light bulb, air. Then it no longer feels warm. it is transformed into radiant energy (light) and thermal energy (heat). In the same way, Electromagnetic energy electrical energy travelling through a wire in Electromagnetic energy is emitted from objects your house to a blender is transformed into as waves. Forms of electromagnetic energy motion energy, thermal energy (heat), and include radio waves, microwaves, visible light, sound energy. and x-rays.

Thermal Energy Electromagnetic waves travel at the speed of Matter is made up of atoms. These atoms light, which is 186,000 miles per second. move (or vibrate) constantly. Atoms vibrate Therefore, a radio wave could circle the Earth faster in hot objects and slower in cold objects. almost eight times in one second, and light Thermal energy is energy from vibrating atoms. travels 93 million miles from the Sun to the The hotter the substance, the more its Earth in only nine minutes. Because molecules vibrate, and the therefore the higher electromagnetic waves are moving, they are a its thermal energy. Since thermal energy form of kinetic energy. involves atoms in motion, it is a form of kinetic energy. Electromagnetic energy can travel through the air, solids, and liquids. In addition, There is a difference between heat and electromagnetic energy can travel through temperature. Think about a cup of water and a space. If it couldn’t, sunlight would never reach swimming pool. They may both have a the Earth! temperature of 78o Fahrenheit, but obviously the swimming pool has much more energy

Adapted from: Forms of Energy, US Energy Information Administration, 2014. Examples of electromagnetic energy: Microwaves are the shortest electromagnetic waves. They bounce around inside the microwave, causing water molecules in the food to start vibrating billions of time each second, transforming the electromagnetic energy into heat energy.

Radar waves 1) are emitted by the radar transmitter, 2) reflect off of the aircraft, and 3) travel back to the radar receiver.

Radar waves are energy that is emitted from a special transmitter. The radar waves reflect off objects, and the reflected waves travel back to the receiver.

Nuclear Energy Nuclear energy is energy stored in the nucleus, or center, of atoms. Because nuclear energy is stored energy it is a form of potential energy.

During nuclear fission, atoms are split apart to form new elements. In nuclear fusion, atoms are fused together to form a new element. Both processes release tremendous amounts of energy.

An example of nuclear energy: In a nuclear reactor, atoms of uranium are split and become atoms of barium and krypton. This releases tremendous amounts of energy. Heat released during nuclear fission is used to turn water into steam to run electrical generators.

Uranium fission

Adapted from: Forms of Energy, US Energy Information Administration, 2014.