Chapter 15 - Energy

15.1 Energy and Its Forms Energy is the ability to do work. Work is the transfer of energy  Work = force x distance

2 types of Mechanical Energy  Kinetic Energy (KE)– Energy of motion KE = ½ mv 2  Potential Energy (PE) – stored energy as a result of position or shape Gravitational Potential Energy – depends on height  GPE = mgh (mass x 9.8 m/s 2 x height) Elastic Potential Energy – PE of an object that is stretched or compressed

Forms of Energy Mechanical Energy – associated with the motion and position of everyday objects  Sum of KE and PE

Thermal Energy – total KE and PE of all the microscopic particles in an object  The greater the thermal energy, the faster the atoms move, the warmer the object is

Chemical Energy – energy stored in chemical bonds  Energy released when bonds are broken can do work

Electrical Energy – energy associated with electric charges

Electromagnetic Energy – form of energy that travels through space in the form of waves  Ex. Visible light, x-rays, gamma rays

Nuclear energy- energy stored in atomic nuclei  Produced by fission and fusion

15.2 Energy Conversion and Conservation Energy Conversion – changing energy from one form to another Law of Conservation of energy – states that energy cannot be created or destroyed

15.3 Energy Resources Nonrenewable energy resources  Exist in limited quantities  Once used, cannot be replaced except over millions of years  Oil, natural gas, coal, and uranium are nonrenewable  Oil, coal, and natural gas (fossil fuels)

Renewable Energy Resources  Can be replaced in a relatively short period of time  Hydroelectric, solar, geothermal, wind, and biomass are renewable

Hydroelectric Energy Energy obtained from flowing water Water flows downhill converting GPE into KE, water turns turbines that are connected to generators

Solar Energy Sunlight that is converted into useable energy  Passive – use sunlight to heat a building – no machinery  Active – sunlight heats collection plates through which water flows

Geothermal Energy Thermal energy beneath earth’s surface  Can be used to generate electricity in some areas, usually near volcanoes

Biomass Energy Chemical energy stored in living things.  Can be converted directly into thermal energy

Conserving Energy Reduce needs Increase efficiency