Physics Energy Review

camshaft

a rotating shaft within the engine that opens and closes the intake and exhaust valves in the engine

crankshaft

Turns the pistons' up and down motions into circular motion

intake valve

a valve that permits the air-fuel mixture to enter the combustion chamber and seals its exit

exhaust valve

where the products of burned gas leave the engine

piston

movable part in the cylinder forced into motion by explosion of fuel

first class lever

The fulcrum is positioned between the effort and resistance

second class lever

The fulcrum is positioned at one end of the bar and the resistance is between the fulcrum and the effort

third class lever

The fulcrum is at one end of the bar and the effort is between the fulcrum and the resistance

first law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

LED

a diode that uses semiconductors to let electricity flow in one direction

LCD

a screen that uses a layer of crystals that align with electric fields to create images; the screen also uses two polarizer layers.

CCD

the device in digital cameras that captures individual photons; uses a photocell

piezoelectricity

this happens when a quartz crystal creates a tiny voltage when it is compressed; this operates the tuning fork in watches

ideal mechanical advantage IMA

how much a machine multiplies force with no frictional interference

actual mechanical advantage AMA

actual amount which a machine multiplies input force; ratio of force out over force in

efficiency

ratio of work out to work in

intake stroke

sinking piston creates a low pressure area in the cylinder; fuel air mixture fills the area

power stroke

piston is forced downward, turning the crankshaft; valves are closed

compression stroke

piston rises, reducing the volume and increasing the temperature

nuclear power

yields highest amount of energy and no emissions, but fuel disposal is a problem

hydroelectric power

no emissions, low expense, but locations limited by available rivers with a steep enough grade

solar (photovoltaic, "PV") power

does NOT use a magnet and coil to generate electricity; good for remote areas; large-scale generation requires lots of materials to make PV panels (and sunlight!)

biomass

uses cornstalks and other bio waste; fuel is not expensive, but it does create carbon emissions

geothermal

can use Earth's heat to boil water to make steam; common in Iceland; small systems can act like heat pumps connected to underground pipes

entropy

the probable direction or trend of events; increasing disorder

heat pump

uses condensation and evaporation to move heat; can be reversed to act as air conditioning

lithium

element that must be mined to manufacture batteries for electric cars and our other devices

coal power plants

often in favor due to available fuel and existing infrastructure; falling out of favor due to high carbon emissions

carbon foot print

the amount of carbon that a person adds to the atmosphere through daily activities / energy use

carbon dioxide and methane

the two leading greenhouse gases that can trap infrared radiation and heat up the climate

wind turbines

devices that use a coil and magnet to convert wind's kinetic energy into electric energy; no emissions; intermittent supply of power

solenoid (coil) and permanent magnet

two objects required to create a speaker; often used to generate electricity

non-renewable resources

coal, oil, uranium, natural gas

fossil fuels

these provide about 60% of the electricity generated in the U.S.; they contribute to climate change since their emissions trap heat ("infrared radiation")

nuclear power stations

these provide about 18% of the electricity generated in the U.S.

first law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

second law of thermodynamics

when energy is changed from one form to another, some useful energy is always degraded into lower quality energy (usually heat); increases disorder

polarizer

A device that permits the passage of light waves vibrating in only one plane; used above and below liquid crystal displays in phones and computers

Robert Hooke

coined the term "cell"; discovered how to create a clock with a spring that could be used at sea; led to longitude navigation