Energy

Give examples of kinetic vs potential energy. WHAT IS ENERGY? What is ENERGY? The capacity to do work and transfer heat. What is WORK? Matter movement. Forms of energy - light, heat, electricity, chemical energy, mechanical energy, and nuclear energy. Give examples of kinetic vs potential energy.

Electromagnetic Spectrum Transverse waves Different wavelengths and frequencies Ionizing radiation - harmful Non-ionizing radiation – not harmful

Heat Energy What is temperature? The average speed of the motion of the molecules in a given sample of matter What is heat? The total kinetic energy of all the moving molecules within a given substance or energy that can be transferred between objects of different temps

How is heat transferred?

Energy Quality An energy source’s ability to do useful work High-quality - organized or concentrated - can perform useful work Electricity, coal, gasoline, sunlight, uranium Low - quality - disorganized or dispersed- can perform little useful work Heat in water, air, etc.

Changes in Matter Physical Change Chemical Change Chemical nature is not changed. What are some examples of physical changes? Chemical Change What is an example? What is a CHEMICAL Equation? Reactants Products

Law of Conservation of Matter All the matter on earth is here and cannot be “thrown away” - there is no “away” Earth is a closed system Matter cannot be created nor destroyed Matter is not consumed

Law of Conservation How does the Law of Conservation apply to pollution?

Nuclear Changes When nuclei of certain isotopes spontaneously break down into one or more different isotopes. Three types: 1. Natural radioactive decay 2. Nuclear fission 3. Nuclear fusion

Natural Radioactive Decay Unstable isotopes - radioisotopes - spontaneously break down and emit: Alpha particles - positively charged helium nuclei Beta particles - high speed electrons Gamma rays - high speed ionizing electromagnetic radiation

Nuclear Fission Nuclei of atoms with large mass numbers are split into lighter nuclei Releases more neutrons and energy Critical mass needed to start reaction Atomic bombs - uncontrolled nuclear fission Damage cells Used in nuclear power plants

Nuclear Fusion Two isotopes of light elements are combined under great heat and pressure to form a heavier nucleus Harder to initiate Thermonuclear weapons The sun

Half-Life Rate of decay Time needed for one half of the nuclei in a radioisotope to decay and emit their radiation Eventually forms a new element Is not affected by temp. pressure, chemical changes, etc. Rule is store for 10 half-lives for safety

Half-Life

Thermodynamics First Law—energy is neither created nor destroyed but it may be converted from one form to another. Energy input always equals energy output You can’t get something for nothing - cannot get more energy out of a system than is put in!!! Second Law (Entropy)—During energy changes, some useful energy is always degraded to lower quality less useful energy (heat). We ALWAYS end up with less useful energy than we started with. An incandescent light bulb - 5 % light, 95% heat

More on 2nd law We can NEVER recycle or reuse high quality energy to do useful work. You get high quality matter and energy in your body, you use it and you add low quality waste matter and heat to the environment. VS

What is Energy Efficiency? A measure of how much useful work is accomplished by a particular input of energy into a system. Always measured as a percent (%). Affects life because high quality matter and energy is used, but the use adds low quality heat and waste back into the environment.

Efficiency (%) = 100 x energy out/ energy in An Example Processes involved in a coal-fired power plant: Efficiency (%) = 100 x energy out/ energy in Process Energy in (MJ) Energy out (MJ) Efficiency (%) Extraction 100 80 Processing 73.6 Transportation 72 Conversion 27 Transmission 25 OVERALL