Transcript ENERGY Study Guide

ENERGY
Study Guide
What Are Kinetic and Potential Energy?
Energy Sources
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Energy – the ability to cause a change in
matter (Movement, or a change in position)
Law of Conservation of Energy – energy
can never be made or destroyed, but it can
change forms
The race car is moving, so it has energy.
Where does it get its energy? It can’t just
make the energy it needs. This is part of the
law of conservation of energy. The race
car’s engine changes the energy stored in
gasoline into movement. The care moves, or
changes position, because one form of
energy changes into another.
Kinetic Energy
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Kinetic energy is the energy of motion. If
something is moving it has kinetic energy.
The faster an object is moving, the more
kinetic energy it has.
An airplane flying
through the air has
more kinetic energy
than a person
riding a bicycle.
Kinetic Energy
Potential Energy
Potential Energy
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Potential energy is the energy an object has
because of its condition or position. For example,
the higher an object is, the more potential energy it
has. So a ball on the roof of a building has more
potential energy than a ball on your desk, because it
can fall farther.
An object can have potential and kinetic energy at
the same time.
As this roller coaster car moves to the top of
the hill, it gains potential energy. The higher
the car rises, the more potential energy it has.
When the car moves down, it has kinetic
energy. As it falls, its kinetic energy increases
and its potential energy decreases.
Click here for the roller coaster animation
Energy Transfer
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Energy transfer- the movement of energy from
one place or object to another.
A
baseball player hits a ball, kinetic energy is
transferred from the bat to the ball.
 A hammer strikes a nail, kinetic energy is transferred
from the hammer to the nail. Can you think of other
examples?
The boy’s kinetic energy is transferred to
the spring, where it changes into potential
energy. As the spring expands, that
potential energy is transferred to the boy as
kinetic energy, bouncing him into the air.
What Are Some Forms of Energy?
Forms of Energy
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Solar Energy- energy that comes from the sun.
The word solar means “of the sun.” People use
solar cells that change light energy from the sun
into electricity.
 Solar
calculators
 Solar panels to heat swimming pools
 Solar panels that provide light and power appliances
in homes or other buildings
Without solar energy, Earth would be just a ball of frozen rock with no life.
The sun is the source of almost all energy on Earth. Light from the sun
helps plants make food and oxygen. Its energy is stored in
fossil fuels- the coal, oil, and natural gas that come from long-dead
plants and animals. The sun’s energy is also the source of weather.
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Other forms of energy come from the sun
directly. Energy from the sun travels as
radiation. The sun provides different types
of radiation.
 Light,
radiation we see
 Heat, radiation we feel
 X rays
 Ultraviolet rays
 Radio waves, which we
hear as static on radios
*some of these rays can be dangerous
Chemical and Mechanical Energy
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Chemical energy- energy stored in fuel. This is
energy that can be released by a chemical
reaction, such as burning. When it is not being
used, it is potential energy. A chemical reaction
is needed to change this potential energy into
kinetic energy.
Our muscles get energy from the food we eat. The
potential energy stored in food is chemical energy.
When it’s released, it gives us kinetic energy to move.
Chemical energy in fuel is used to keep this remote-controlled
helicopter flying in the air.
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Mechanical energy- the combination of
all the potential and kinetic energy that
something has.
This windup toy has a key attached to a spring.
When you turn the key, you wind up, or tighten, the
spring, giving the toy potential energy. The tighter it is
wound up the more potential energy it has stored.
When the toy is moving, it has kinetic energy. Since
the spring is still partly wound up, the toy also has
some potential energy left. The toy’s mechanical
energy is a combination of its potential energy and its
kinetic energy.
Chemical energy is stored in fireworks.
Is chemical energy potential or kinetic energy?
Electricity
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Electricity, or electric energy- energy that
comes from an electric current. An electric
current results from the movement of electrons.
Electrons are particles found in atoms. You can
see some effects of electric energy when you
use appliances. You may have even felt electric
energy. Have you ever walked across a rug on
a dry day and then touched a doorknob? You
probably felt electric energy in the form of a
small shock.
Simplest model of the atom
Static Electricity
Sound
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Sound- energy in the form of vibrations that travel through
matter. Sound vibrations pass through the particles of matter
in a kind of domino effect. When a vibration reaches a
particle of matter, that particle starts to vibrate, too. If it’s
close enough to other particles, they also start to vibrate. In
this way, sound vibrations can spread out, not just in a
straight line, but in all directions.
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Sound travels through air, so people can hear sounds-even quiet
ones-at a distance
Hearing begins deep inside the ear in a thin membrane called
the eardrum.
You can place your hands on a radio or TV and feel the sound
vibrations.
Some people with hearing disabilities have been able to become
dancers by feeling the vibrations of the music through their feet.
Sometimes you can feel sound, like at a fireworks show. Many
fireworks produce not only bright colors, but also loud whistles,
pops, and bangs. You can often feel the energy of these sounds
on your body.
Sound
Changing Energy Forms
Energy is constantly being changed from one form
to another in order to make it more useful to us.
 The
batteries in a flashlight contain chemical energy,
but the flashlight bulb gives off light. Where does the
light come from? The batteries’ chemical energy
changes into electric energy. Then the bulb in the
flashlight changes the electric energy into light
energy.
 Microphones change sound energy into electric
energy, which is amplified, or increased. Speakers
change the electric energy back into sound.
How is Heat Transferred?
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All matter is made up of tiny particles that are
always moving. Since they move, they have
kinetic energy, also called thermal energy.
Heat- the transfer of thermal energy between
objects with different temperatures.
Thermal energy travels from a warmer object to
a cooler object.
Energy from the stove burner flows through
the pot and into the water, causing it to get
hot. Energy doesn’t travel from the lowtemperature water to the high-temperature
burner.
Heat
Temperature
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Temperature- the measurement of the average
kinetic energy of all the particles in a substance.
You can measure temperature with a
thermometer. The number shown on a
thermometer is related to the amount of kinetic
energy in a substance.
Some systems are very efficient at transferring
thermal energy. A System is a set of parts
acting together as a whole object.
A burner, a pot, and water are a system through which
Thermal energy moves. The burner transfers thermal
Energy to the pot. The pot transfers thermal energy to
The water. As the water receives more and more
Thermal energy, its particles move faster.
Thermal Energy Transfer
There are three ways heat can move
through a system.
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Conduction- the transfer of thermal energy from one
object directly into another (heat from the iron moves
directly into the clothing)
Convection- the transfer of thermal energy through the
movement of a gas or a liquid. As a gas or liquid is
heated, the heat causes it to move upward, carrying heat
to the area above the heat source (heated air moves up,
carrying thermal energy to the air above it)
Radiation- the transfer of energy by waves that move
through matter and space. Not all radiation from the sun
reaches Earth’s surface. Some of it is reflected back into
space by the atmosphere. Reflection occurs when heat
or light bounces off an object. (Radiation carries thermal
energy from the lamp to the food)
Insulators and Conductors
Insulator- anything that slows the movement
of thermal energy (coolers, Styrofoam
cups, fur coat)
The lunch bag prevents heat in the air from moving
Into the bag. This keeps the food in the bag cool.
Conductors- anything that allows thermal
energy to move through it easily (most
metals).
The cookie sheet is a conductor. The
oven mitt is an insulator.
How Do People Use Energy?
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Nonrenewable energy Resources
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Fossil- the remains or traces of past life found in
sedimentary rock. Fossil fuels are fuels that formed from
the remains of once-living things, for example coal, oil, an
natural gas.
 Resource- any material that can be used to satisfy a need.
 It takes millions of years for coal, oil, and natural gas to form.
When supplies are used up, there will be no more. This is
why coal, oil, and natural gas are called nonrenewable
resources. These materials, once used up, cannot be
replaced within a reasonable amount of time.
 Conservation- using less of something to make the supply
last longer
Renewable Energy Resources
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Renewable resource- a resource that can
be replaced within a reasonable amount of
time, for example solar energy (sun),
hydroelectric energy (water), and wind
energy
Natural Resources
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There is a great deal of information to process in this
unit. Some of the information is not in your
textbook. Please make sure study off of this guide.
Don’t wait until the last minute to begin studying for
the test.
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Remember, I am available to answer questions and
help you with any concept you don’t understand. I
stay after school almost every day. I will have tutorial
tomorrow and Thursday from 4-5pm.
Happy Studying 