# Quarterly

• Potential energy - energy that is stored in a person or object

• Gravitational Potential Energy - Potential energy due to the position of an object above Earth’s surface (Has the potential to fall)

• Gravitational potential energy (GPE) = weight × height

• A Newton ∙ meter is the energy needed to move a weight of 1 Newton over a distance of 1 meter

• Elastic Potential Energy - Potential energy due to an object’s shape

• Happens when an elastic object is stretched or compressed

• Farther its compressed, more energy

• Food and batteries both contain chemical energy

• Kinetic Energy- The energy of moving matter

• Anything that is moving has kinetic energy

• The amount of kinetic energy in a moving object depends directly on its

mass and velocity

• KE= ½ mass x velocity2

• Joules, or n x m is the SI unit for energy

• Energy -  the ability to cause changes in matter, can exist in many different forms

• Can change from one form to another

• The six forms of energy:

• Mechanical

• Chemical

• Electrical

• Light

• Thermal

• Sound energy

• Nuclear energy

• Mechanical energy- the energy of movement

• Chemical energy- energy that is stored in the bonds between the atoms of compounds (if bonds are broken, the energy is released and can convert into other forms

• Electrical energy- the energy of moving electrons

• Electromagnetic energy- energy that travels through space as electrical and magnetic waves

• Examples are Light flooding the stage, include radio waves, microwaves, X rays, and gamma rays

• Thermal energy - the energy of moving atoms of matter

• Sound energy - a form of mechanical energy that starts with a vibration in matter

• the singer’s voice starts with vibrations of his vocal cords, which are folds of tissue in his throat

• Nuclear energy - energy that is stored in the nuclei of atoms because of the strong forces that hold the nucleus together

• Energy can be released in nuclear power plants by splitting nuclei apart

• Energy conversion - process in which one kind of energy changes into another kind

• Obeys the law of conservation of energy, which states that energy cannot be created or destroyed

• Examples:

• Sound, Mechanical, electrical, chemical, and thermal energy

• One form of energy often forms into two different forms

• Mechanical energy commonly changes between kinetic and potential energy

• Nonrenewable resources are natural resources that are limited in supply and cannot be replaced as quickly as they are used up

• Includes fossil fuels such as oil (Petroleum) and the radioactive element uranium

• Also coal, and natural gas

• Nuclear energy

• Fossil fuels are mixtures of carbon and hydrogen that formed over millions of years from the remains of dead organisms

• Are burned in power plants to produce electrical energy

• They fuel cars, warm homes, and provide energy for many other thing, such as electricity.

• After the plants and other organisms died, their remains gradually changed to fossil fuels as they were covered and compressed by layers of sediments

• Petroleum and natural gas formed from ocean organisms and are found together

• Coal formed from giant tree ferns and other swamp plants

• When fossil fuels burn, they produce thermal energy, water vapor, and carbon dioxide

• Global warming is effected by the carbon dioxide

• Sulfur oxide form acid rain

• Nitrogen oxides cause smog

• The supply of uranium in the world is quite limited, and cannot be replaced once it is used.

• accidents at nuclear power plants have the potential to release large amounts of harmful radiation into the environmentWind is moving air, so it has mechanical energy that can do work

• The wind turbines change the kinetic energy of the wind to electrical energy, though only certain areas of the world get enough steady wind to produce much electricity

• Many people also think that wind turbines are noisy, dangerous to birds, and unattractive in the landscape

Sunlight

• Solar energy is electromagnetic energy, a form of energy that travels through space in electric and magnetic waves

• Solar energy can be used to heat homes and produce electricity in solar cells

• Not good for cloudy areas

Moving Water

•  Mechanical energy of rapidly flowing water can turn a turbine and generate electricity (Hydroelectric power)

• Flows through a waterfall or through a dam

Biomass

• Stored chemical energy in organic matter or wastes (trees,  other plants, or wastes from homes and industries)

• Usually burned to heat homes, cook, or generate electricity

• Releases air pollution and contributes to global climate change

• Used to make ethanol (fuel that is added to gas)

• Reduces available land for food production

Geothermal Energy

• Heat energy from below earths surface

• Used to heat homes or generate electricity

• Pumps water underground where it is heated and then pumps the warm water back to the home or power plant

• Thermal energy of the water can be used directly to heat the home, or to create steam and generate electricity

• Installation can be expensive because of the need to drill through underground rocks, but the energy it uses is free

• Oil is the single most commonly used energy resource in the U.S., followed by natural gas, and then by coal (all are nonrenewable)

• Nonrenewable- resources that are limited in supply and cannot be replaced as quickly as they are used up

• Renewable sources provide only 8 percent of all energy used in the U.S. Renewable resources are natural resources that can be replaced in a relatively short period of time or are virtually limitless in supply (sunlight, geothermal energy from under Earth’s surface, wind, biomass and hydropower)

• People in the us use far more energy than other nations, mostly from oil

• Conservation-Saving resources by using them more efficiently, using less of them, or not using them at all

Ways to conserve transportation energy:

• plan ahead to avoid unnecessary trips

• take public transit such as subways instead of driving

• drive an energy-efficient vehicle when driving is the only way to get there

How to conserve energy at home:

• turn off lights and unplug appliances and other electrical devices when not in use

• use energy-efficient light bulbs and appliances

• turn the thermostat down in winter and up in summer

•  The ability to move matter or change matter in some other way or the ability to do work (In work energy is transferred from object to another)

• Is expressed in the same unit that is used for work (Joule, Newton, meter)

• W= N ∙ m

• Energy of moving a racket is mechanical energy

• Chemical energy is food

• There is also electrical, thermal, light, sound energy, kinetic energy, potential energy

• Kinetic energy- energy of moving matter

• Potential energy- energy that is stored in matter

• Wedge - a simple machine that consists of two inclined planes, giving it a thin end and thick end

• A wedge is used to cut or split apart objects

• Force is applied to the thick end of the wedge, and the wedge, in turn, applies force to the object along both of its sloping sides

• A wedge applies more force to the object (output force) than the user applies to the wedge (input force), so the mechanical advantage of a wedge is greater than 1

• A longer, thinner wedge has a greater mechanical advantage than a shorter, wider wedge

• With all wedges, the trade-off is that the output force is applied over a shorter distance, so force may need to be applied to the wedge repeatedly to push it through the object

• Screw - a simple machine that consists of an inclined plane wrapped around a central cylinder

• Examples - Screw for wood, caps,

• Move objects to a greater depth (or higher elevation) by increasing the force applied to the screw

• When you use a screw, you apply force to turn the inclined plane. The screw, in turn, applies greater force to the object, such as the wood or bottle top

• When you use a screw, you apply force to turn the inclined plane. The screw, in turn, applies greater force to the object, such as the wood or bottle top (The advantage is always greater than 1)

• More turns of the screw are needed to do the job because the distance over which the input force must be applied is greater

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• Lever - a simple machine consisting of a bar that rotates around a fixed point

• The Fulcrum - the fixed point of a lever

• A hammer changes the direction of the force applied to the hammer, and increases the strength of the force that is applied to it

• The hammer decreases the distance over which the force is applied

• Based on the location of input and output forces, there are three basic types of levers, called first-class, second-class, and third-class levers

- First class- a seesaw

- Second class - wheelbarrow

- Third class- Hockey stick

• In first class levers - When the input and output forces are on opposite sides of the fulcrum, the lever changes the direction of the applied force.

• With second class and third class levers -  When both the input and output forces are on the same side of the fulcrum, the direction of the applied force does not change.

• Second class, may occur with first class - When the input force is applied farther from the fulcrum than the output force is, the output force is greater than the input force, and the ideal mechanical advantage is greater than 1

• Wheel and axle - a simple machine that consists of two connected rings or cylinders, one inside the other

• The inner ring or cylinder is called the axle, and the outer one is called the wheel

• In a wheel and axle, force may be applied either to the wheel or to the axle (Input force)

• Doesn't change direction of the input force

• A wheel and axle may either increase or decrease the input force, depending on whether the input force is applied to the axle or the wheel

• When the input force is applied to the axle, like a ferris wheel, the wheel turns with less force (Mechanical advantage is less than 1)

• When the input force is applied to the wheel, like a doorknob, the axle turns over a shorter distance but with greater force, so the mechanical advantage is greater than 1