Group:
Kathy Burns, John Leimer, Sherry Rich, Kim Scholes
Module --- Energy Transfer and Properties of Waves
Major Concepts:
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First Law of Thermodynamics / Law of Conservation of Energy
Energy Transfer
Energy Diagrams
Mechanical Energy
Light Energy
Thermal Energy
Properties of Waves
Grade Level:
Physical Science --- 8th and 9th Grades
Missouri Standards:
Standards:
Standard 1: Students in Missouri public schools will acquire a solid foundation which
includes knowledge of properties and principles of matter and energy.
Standard 2: Students in Missouri public schools will acquire a solid foundation which
includes knowledge of properties and principles of force and motion.
By the end of the 8th grade:
Students should know that energy is required to produce changes in matter and to
do work.
Students should be able to design, conduct, and communicate about an
investigation that shows the relationship between energy and changes in matter.
By the end of the 8th grade:
Students should know that energy travels through matter as waves.
Students should be able to identify waves as mechanical or electromagnetic and
identify common wave properties.
Overview:
Prior to this unit (energy transfer and properties of waves) students investigated energy
and matter in motion. Major concepts discussed were force, motion, speed, velocity,
acceleration, and work. During this unit, students will concentrate on basic principles
related to energy transfer and wave properties. Students will be responsible for
describing energy transfer (mechanical, light, and thermal) by completing energy
diagrams associated with five development activities. During the second portion of this
unit, students will discuss wave properties and their relationship to motion along a spring
and within a ripple tank. After completing this unit, students will begin investigating
energy sources including fossil fuels. Alternative energy sources will also be discussed
as a way to protect our environment and conserve fossil fuels.
Background
Energy
Energy is the ability to do work. There are many different forms of Energy: heat,
chemical, electromagnetic, nuclear and mechanical. Mechanical energy is the energy of
associated with motion. Electromagnetic energy is energy produced by moving electric
charges. Thermal energy is energy of heat.
Energy can only be converted from one form to another, but is never created or
destroyed. This is referred to as the Law of Conservation of Energy. For example solar
energy from the sun can change to electrical energy in a solar cell. The electrical energy
can be changed to light energy as in a light bulb. Energy moves from one place to
another in the form of waves.
Sun
Solar Panel
Solar Energy
Electrical Energy
Light Bulb
Light and Heat
Waves
Light (electromagnetic) energy moves by transverse waves. The disturbance is
perpendicular to the direction the wave is moving. These waves can move through empty
space, they do not need a medium.
disturbance
Direction wave is moving
Sound energy moves by longitudinal waves. Longitudinal waves move parallel to the
direction the wave is moving. These waves must have a medium to move through.
disturbance
Direction wave is moving
Background cont.
Properties of waves:
Amplitude—the distance from the crest or trough to the normal (resting position).
Wavelength
crest
Normal
Amplitude
trough
Frequency—how many times a wave occurs with in a certain time.
Wavelength—the distance from one point on a wave to the same point on the next wave.
Speed—how fast a wave travels is determined by dividing the distance a pulse travels by
the time it takes to travel that distance. Changing the medium that a wave is
traveling or the tension in the medium through can affect the speed of a wave.
Changing the frequency or Amplitude of the wave does not affect speed.
Changing the frequency of a wave changes its wavelength inversely. The greater the
Frequency the less the wavelength. Amplitude is not affected by frequency, wavelength
or speed.
Interactions of waves:
Reflection—a wave bounces off a barrier. Example: Light reflects off of a mirror.
Reflected Wave
Incidence Wave
(In coming wave)
Refraction—a wave’s speed is changed as it passes through a transparent medium and the
wave is bent. Example: A straw looks bent in water because the light waves are change
speed as they move through a different medium and bends.
www.ps.missouri.edu/.../ refract/refraction.html
Diffraction—a wave bends around a barrier. Waves in water will bend around obstacles.
http://www.kettering.edu/~drussell/Demos/waves/wavemotion.html
http://www.physicsclassroom.com/Class/waves/wavestoc.html
http://www.glenbrook.k12.il.us/gbssci/phys/Class/sound/u11l1b.html
http://www.eia.doe.gov/kids/energyfacts/science/formsofenergy.html
http://fi.edu/guide/hughes/energyconservation.html
http://www.glenbrook.k12.il.us/gbssci/phys/Class/waves/u10l2a.html
Misconception:
Background: In the activity involving the radiometer the students may have
misconceptions about what causes the movement of the vanes. The student may see the
light from the flashlight causing the movement without taking into account the increase
in thermal energy caused by the interaction. The misconception may cause them to view
the energy interaction as that of stored chemical and motion energy instead of an increase
in light energy and a decrease in thermal energy.
In the dropper popper activity the student may have difficulty separating the
person’s dropping the popper from the energy released from the popper itself. The
student may not view the energy as coming from the popper itself in the form of stored
elastic energy.
Misconceptions associated with the activity involving shining the flashlight in the
students eye is that the eye allows the person to see without accounting for the interaction
with the light. The students do not view the light as an entity existing on its own.
Similarly, when participating in the activity dealing with the Mylar the students might
attribute the events that occur to the Mylar and the flashlight. The light itself may not be
viewed as interacting with the Mylar in any particular way to allow for the students to
view the different occurrences.
Numerous misconceptions may exist among the students relating to waves and
their properties. In the boat activity the student may believe that the wave created will
cause the boat to move forward or backward. The student may believe the boat (matter)
will be moved, when the actual movement is the energy transferred from the wave.
Students may hold the misconception that the speed of the waves in the same medium is
affected by the other wave properties: amplitude, wavelength, and/or frequency.
Through their interaction with the slinky activity they will learn that an inverse
relationship exists between the frequency and wavelength, resulting in them having no
affect on the speed of the wave in the same medium.
The student may hold the misconception that a fixed or free barrier does not affect
the wave travel. The student may not believe the fixed barrier will cause the wave to
return inversely as it returns from the barrier. The students will observe this in the slinky
activity.
Student Objectives:
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Students will diagram the transfer of energy between two objects (hand and cart).
Students will create energy diagrams to describe the transfer of energy
(mechanical energy, light energy, and thermal energy).
After several development activities, students will review the key concepts related
to energy transfer (First Law of Thermodynamics / Law of Conservation of
Energy, mechanical energy, mechanical energy, light energy, and thermal
energy).
Students will analyze situations in life describing how energy is transferred
between objects.
Students will make predictions and observe wave characteristics.
Students will be able to define wavelength, frequency and speed of waves.
Students will observe the effects of tension on a spring and the speed of waves.
Students will identify wave characteristics in a ripple tank.
Lesson Activities:
Elicitation Activity --- Push Cart Demonstration
PET Project 2004
Cycle 1
Activity 2
Motion Energy
Instruction --- Constructing Energy Diagrams
PET Project 2004
Cycle 1
Activity 2
Motion Energy
Cycle 5
Activity 2
Light Energy
Cycle 6
Activity 1
Shiny Surfaces and Seeing
Cycle 6
Activity 3
Non-Shiny White and Black
Surfaces
Consensus Ideas --- Push Cart Demonstration
PET Project 2004
Cycle 1
Activity 2
Motion Energy
Activity 5
Constructing Explanations
Development Activities
Radiometer
Arbor Scientific
Dropper Popper
Arbor Scientific
Flashlight / Eye
PET Project 2004
Mylar
PET Project 2004
Black and White Card
PET Project 2004
Class Discussion --- Basic Concepts
Application Activity --- Baseball Player
PET Project 2004
Cycle 1
CPU: Activity I-E Waves and Boats
Activity I-D2 How do Waves on a Spring Behave
Activity I D3 Exploring waves in a Ripple Tank
Greenhouse Effect : Holt Physical Science, 1994
Materials:
Pushing the car – motion cart, track – 1 set for teacher demonstration.
Rubber band & car – toy car with a “pull-back motor”, large rubber band. One set for
every group of 4 students.
Radiometric – radiometer (if no sunlight use overhead projector)– 1 for demonstration
Dropper popper – dropper popper – 1 for each group of 4 students. Or may be done as a
demonstration by the teacher.
Flashlight / eye activity – flashlight, bulb, socket, battery, wires. 1 set for each group of 4
students.
Mylar activity – white paper square, small Mylar square, flashlight.
White vs. black card – flashlight(new bulb), tubular bulb in socket, white card, gray card,
black card, flat mirror, piece of white paper(81/2 x 11), card with wrinkled aluminum
foil wrapped around it. One set for each group of 4 students.
Waves & boats – small toy boat, long plastic container(about 20-24” long, 4-8” deep, and
narrow), water, small wooden block. One set for a teacher demonstration.
Waves and a spring – slinky, stopwatch, meter stick, 2 m long string. One set for each
group of 4 students.
Waves in a Ripple Tank-Ripple tank, block of wood, stopwatch, ruler, overhead projector
Greenhouse Effect- aquarium, black material (cloth), 2 thermometers, plastic wrap, light
source
Time Required:
Day 1 --- Pre-test, Elicitation Activity, and Instructions on Constructing Energy Diagrams
(50 minutes)
Day 2 --- Development Activities (Five Lab Stations)
(90 minutes)
Day 3 --- Consensus Ideas, Class Discussion of Basic Concepts, and Application Activity
(50 minutes)
Day 4 --- Elicitation Activity, D1, and D2
(50 minutes)
Day 5 --- D3 and Class Discussion of Basic Concepts
(50 minutes)
Day 6 --- Application Activity and Post-test
(50 minutes)
Assessment Tools:
Observation of student activities
Student demonstrations
Student discussions
Lab sheets and worksheets
Pre and Post test Questions
Suggested questions
1. Jose has a toy wind-up car. Inside the toy car is a coiled spring. Jose holds the
car on the floor, winds the spring up, and then lets the car go.
While Jose was winding the spring up
a. energy was being created.
b. energy was being destroyed.
c. energy was being transferred.
d. None of the above
2. Draw an energy diagram representing Jose and the wind-up car.
3. During a football game, you rub your hands together to keep warm. Draw an
energy diagram representing this action.
4. If your teacher gives a stretch out slinky a pluck, a wave will travel down the
length of the slinky.
What exactly is it that moves forward?
5. What are two different types of wave travel?
6. If the frequency at which you move the end of a slinky back and forth is
increased, the
a. wavelength of the wave on the slinky will increase.
b. wavelength of the wave on the slinky will decrease.
c. wavelength of the wave on the slinky will stay the same.
7. A greenhouse is a structure made mostly of glass, why does the air in a greenhouse
get hot during the daytime?
8. Will a thick rope carry waves as easily as a thin rope?
9. When you throw a stone into the water, how does it start the motion of the wave?
10.
How does spacing of water waves relate to their wavelengths?
11.
Aluminum foil is shiny like a mirror, yet you can’t see your reflection in a piece
of crumpled aluminum foil. Explain.
12.
Make an energy diagram from the sun (solar energy) to your radio.
13. Explain the statement: Energy is neither created or destroyed it only changes
forms.
14. Label amplitude, the normal, and wavelength on the diagram.
15. If frequency of a wave increases what will happen to the:
a. wavelength
b. speed of the wave
16. Describe the difference between longitudinal and transverse waves.
17. In the boat activity and the slinky activity you observed waves traveling through
various medium (water and the slinky). What is it that was actually moving?
18. If you increase the tension of the slinky by keeping it the same length, but pull
more coils into your hand before you release it, does the speed of the traveling
wave increase, decrease, or stays the same? Explain your answer.
19. If the amplitude of the wave increases, which of the following will be affected?
(a) Frequency (b) Speed (c) Wavelength (d) None of the Above
20. A student drops a ball held in their hand, from shoulder height. What is the
energy source in this interaction?
21. A student can choose to sit on either a black chair or a white chair which have
both been sitting outside in the sunlight all day. How does the idea of energy
transfer affect the student’s choice of chairs?
Bibliography:
Cuevas, M.M. and W.G. Lamb. Holt Physical Science. Holt, Rinehart and
Winston, Inc. 1994.
http://www.kettering.edu/~drussell/Demos/waves/wavemotion.html
http://www.physicsclassroom.com/Class/waves/wavestoc.html
http://www.glenbrook.k12.il.us/gbssci/phys/Class/sound/u11l1b.html
http://www.eia.doe.gov/kids/energyfacts/science/formsofenergy.html
http://fi.edu/guide/hughes/energyconservation.html
http://www.glenbrook.k12.il.us/gbssci/phys/Class/waves/u10l2a.html