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 mv2

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/s2 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