Chapter 5: Energy: Forms and Changes
Energy is the ability to do work Energy is the ability to do work. Energy can be in many different forms and is all around us! Living organisms need energy for growth and movement. The energy for these processes comes from the foods we eat.
The 2 states of energy are: 1. Kinetic Energy 2. Potential Energy
Kinetic Energy is energy of motion Kinetic Energy is energy of motion. The faster an object is moving, the more kinetic energy it has. The word “kinetic” means motion.
Kinetic energy is directly related to the velocity of an object. Formula: K.E. = (mass x velocity2) / 2 According to this formula, if either the mass or velocity of an object increases, the amount of kinetic energy increases!
Potential Energy is energy of position. When an object is located in such a position that movement could easily occur, it has a great potential energy. Example: stretched rubber band Potential Energy is stored energy!
Potential energy that is dependent on height and weight is called gravitational potential energy. The more an object weighs and the higher up from the ground it is, the more G.P.E. Formula: G.P.E. = weight x height
Energy, like work, is measured in Joules. Energy appears in many forms. The 5 main forms of energy are mechanical, thermal, chemical, electromagnetic, and nuclear.
Mechanical Energy Mechanical energy is energy associated with motion. When any type of matter is moving, it has mechanical energy! Examples: water moving wind blowing Sound
Thermal Energy Thermal energy, or heat energy, is created by the movement of atoms in a substance. The faster the atoms move, the more thermal energy they have. Thermal energy usually results from friction. Thermal energy causes changes in the temperature and phase of any form of matter. Example: melting of ice
Chemical Energy Chemical energy is energy that is stored in chemical bonds. This energy can either be absorbed (endothermic) or released (exothermic). Examples: burning of fuel digestion of food
Electromagnetic Energy Electromagnetic energy is energy associated with moving charges. This energy can be carried by electricity, light, X-rays, radio waves, and laser light.
Nuclear Energy Nuclear energy is energy produced when the nucleus of an atom splits (Fission) or when two nuclei join (Fusion). Nuclear energy is the most concentrated form of energy.
Energy has the unique ability to change from one form to another or move from one object to another. Changes in the forms of energy are called energy conversions.
The 2 most common energy conversions are: Kinetic Potential Potential Kinetic
Other Examples of Energy Conversions: photosynthesis (electromagnetic chemical) Solar panels (light electricity) Motors (chemical mechanical) Batteries (chemical electromagnetic)
The Law of Conservation of Energy When energy is converted from one form to another, the total amount of energy stays the same. Energy can neither be created nor destroyed!
Einstein’s Experiment In 1905, Albert Einstein deducted his famous Theory of Relativity, E = mc2. He proved that matter and energy are related. That is: If matter is destroyed, energy is created If energy is destroyed, matter is created
Nonrenewable Resources These are substances that are used faster than they are formed. They include fossil fuels, which form over millions of years from the remains of prehistoric plants and animals. When burned, these substances release CO2, which threatens to warm our planet
Renewable Resources These are substances that are replaced faster than they are used. These include solar, hydroelectric, wind, geothermal, and biomass.