Download Name: Chapter 14: Changing Forms of Energy Words to Know

Name:_______________________
Chapter 14: Changing Forms of Energy
Words to Know:
1. Energy: the ability to do work or cause a change
2. Kinetic energy: energy due to motion
3. Potential energy: energy that is stored in an object due to its position or arrangement
4. Electromagnetic radiation: energy that travels through space in the form of light and other types of energy
5. Thermal energy: the total of all the kinetic and potential energy of the atoms in an object
6. Conduction: the transfer of thermal energy between objects that are in contact
7. Convection: the movement of warm liquids or gases to cooler areas
Lesson 1: What is energy?
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There are many forms of energy and it can change between them; BUT energy cannot be made or destroyed
Energy can change an object’s motion, color, shape, temperature, or other qualities
Forms of energy:
o Sound
o Chemical (chemical bonds)
o Thermal (heat)
o Light
o Nuclear (nucleus of an
o Electricity
atom)
o Magnetism
o Mechanical (motion)
Energy CANNOT be made or destroyed
Energy CAN move from one object to another
Energy CAN change from one form to another
o Think about fireworks: chemical energylight, sound, and thermal energy
Every time there is a change in energy some of it is given off as unusable heat
Kinetic energy is due to motion. Speed and mass effect kinetic energy
o Speed: the faster an object moves, the more kinetic energy it has
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Swinging a hammer slowly vs. quickly
o Mass: the more mass an object has, the more kinetic energy is has
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A sand castle being hit by a beach ball vs. a basketball
At any particular SPEED a moving object with more MASS has more kinetic energy
Friction can cause kinetic energy to turn into thermal energy (rubbing hands together)
Potential energy (or ‘stored’ energy) is energy that is not causing any changes NOW, but could cause changes in
the FUTURE
There are several different kinds of potential energy
The object’s position determines its type of potential energy
Potential energy often turns into kinetic energy- when the object starts moving (stretched rubber band, north poles
of 2 magnets, electrons of atoms…)
Chemical energy is energy of the electrons that form the bonds between atoms in molecules (chemical energy is a
form of potential energy)
Nuclear energy is the potential energy that holds protons inside the nucleus of an atom
Lesson 2: What is sound energy?
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Sound is a wave of vibrations that spread from its source
Vibration is the back-and-fourth motion of an object
Sound waves travel through materials and vibrate the molecules in different patterns, this causes sound
Frequency is the measure of how fast the particles are vibrating (the greater the frequency, the higher pitch the
sound is
The louder the sound, the more energy the waves have, loudness is measure in “decibels”
Your voice is made up of sound waves
o Your vocal cords vibrate and cause the air around to vibrate too
o These vibrations travel outward through the air in all directions
Sound can travel through solids, liquids, and gases, but NOT vacuums
o A vacuum is empty space that contains no particles (no vibrating particles means that no sound can exist)
Three things can happen when sound waves hit a board
o Sound waves can bounce back
o Sound waves can be absorbed
o Sound waves can pass through to the other material
Sound moves at different speeds through different materials (faster through air than water)
Reflections of sound off of surfaces is called an echo
Sound transfers energy: soundproof walls absorb the sound waves but some of it turns into thermal energy
Sound starts as some type of energy which causes an object to vibrate (your eardrum absorbs the energy and
causes it to vibrate, you hear sound)
Name:_______________________
Lesson 3: What is light energy?
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Visible light is a small portion of the electromagnetic spectrum. It behaves in different ways
o It can travel in straight lines
o It can reflect off objects
o It can bend and pass around or through objects
Visible light of different wavelengths create different colors
Light travels in waves that have certain lengths and frequencies
Light travels at different speeds through different objects
Light is a form of electromagnetic radiation: a combination of electrical and magnetic energy
Electromagnetic radiation comes from the sun to the Earth
o Stars give off a mixture of different kinds of radiation, visible light and radio waves
In order for you to see something it must give off wavelengths of visible light
Some types of electromagnetic radiation have shorter wavelengths (ultraviolet, X-ray, gamma ray radiation)
o These have higher frequencies and more energy
Some types of electromagnetic radiation have longer wavelengths (infrared waves, microwaves, radio waves)
o These have lower frequencies and lower energy
Light travels fastest through a vacuum and slower through air and water
Light moves in straight lines. It reflects, bends, or refracts when it enters a new material at an angle
A prism is a transparent object that separates light into different wavelengths (example: white light enters a prism
and comes out separated into colors)
o Different wavelengths refract at different angles causing colors to separate from each other
Objects can block the path of light causing a shadow
When light is absorbed, the light energy is changed into thermal energy
Convex means thicker in the middle
o Bends light rays to make objects look larger
Concave means thinner in the middle
o Bends light rays to make objects look smaller
Lesson 4: What is thermal energy?
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Thermal energy is the total of all the kinetic and potential energy in the atoms of an object
When heat is added to any object the amount of kinetic energy in its atoms increases (its molecules move faster)
o This causes the object’s thermal energy to increase
Changes in thermal energy lead to changes in physical phase
o The liquid state of a substance always has a higher thermal energy than its solid form
Temperature is a measure of thermal energy (use a thermometer)
Thermal energy flows between materials that have different temperatures (naturally flows from warmer to cooler
objects)
Heat moves in three ways: conduction, convection, and radiation
Conduction is the flow of hear between objects that are touching (the stove heating a pan)
Convection is the movement of warm liquids/gases to cooler areas (cool water sinking under warm water in a fish
tank)
Radiation is the movement of energy by electromagnetic waves (radiation from the sun warming a greenhouse)