# 9P.2.2.2 Change

**Benchmark: 9P.2.2.2.1 Energy of Moving Objects**

Explain and calculate the work, power, potential energy and kinetic energy involved in objects moving under the influence of gravity and other mechanical forces.

**Benchmark: 9P.2.2.2.2 Forces & Change in Velocity**

Describe and calculate the change in velocity for objects when forces are applied perpendicular to the direction of motion.

*For example:* Objects in orbit.

**Benchmark: 9P.2.2.2.3 Momentum & Energy**

Use conservation of momentum and conservation of energy to analyze an elastic collision of two solid objects in one-dimensional motion.

### Overview

**MN Standard in Lay Terms**

Mechanical energy is not created or destroyed. It can change its appearance, form, and function without changing its energy to heat and sound in situations where air resistance and friction are not present.

Mechanical forces or interactions acting along an objects direction of motion is called doing work on an object

(Work = F_{ll}*d ) and creates an interplay of transfer in forms of energy that can be categorized as changing the potential and kinetic energies associated with an object within the system of interactions. If forces such as friction exist in the interactions energy is transferred to an equivalent amount of heat, (generally treated as a non-mechanical energy form), and is removed from the total amounts of mechanical potential and kinetic energies associated with an object. In this situation mechanical energy associated with the object is said to be non-conserved. In the situations when the transfer of energy to non mechanical forms is insignificant, the sum of the mechanical energies associated with an object remain constant as the energy transfers forms and the total energy is said to be conserved. Situations like this are traditionally treated in the beginning study of physics because they allow students to easily measure and visualize energy transfers and consider the conservation idea. Instructors should allow students to explore and formulate these relationships both conceptually and mathematically by experiment. While all problems involving energy can be considered to be the result of work being done on an object due to various forces, physicists classify some forces as conservative, such as gravitational and elastic forces, and problems can be conveniently formulated by looking at energy transfers as changes in potential energies associated with these forces rather than as the work done by these forces giving a unique insight into how energy behaves or transfers among forms in the universe. The SI unit of energy transferred to an object is equivalent to 1 Newton of force acting parallel to an objects displacement of 1 meter and is given the special derived unit called the Joule. 1 N*m is equivalent to 1 Joule (J).

The total amount of energy in the universe is always the same and transfers between forms.

Energy can be transferred between objects, and can change its form. However, energy is neither created nor destroyed. (Law of Conservation of Energy)

Momentum is always conserved in an isolated system.

In an isolated system of interacting objects, such as collisions, momentum is conserved in all situations regardless of the conservation of energy.

**MN Standard Benchmarks**

9P.2.2.2.1 Explain and calculate the work, power, potential energy, and kinetic energy involved in objects moving under the influence of gravity and other mechanical forces.

9P.2.2.2.2 Describe and calculate the change in velocity for objects when forces are applied perpendicular to the direction of motion. For example: Objects in orbit.

9P.2.2.2.3 Use conservation of momentum and conservation of energy to analyze an elastic collision of two solid objects in one-dimensional motion.

**The Essentials**

For Fun and Discussion:

The Way Things Go film 1987 clips one two and three 9P.2.2.2.1

Adam Sadowsky engineers a viral music video

The band "OK Go" dreamed up the idea of a massive Rube Goldberg machine for their next music video -- and Adam Sadowsky's team was charged with building it. He tells the story of the effort and engineering behind their labyrinthine creation that quickly became a YouTube sensation.

This Too Shall Pass Rube Goldberg video by Ok Go 9P.2.2.2.1

**NSES**** - **Physical Science Content Standard B. P. 180

CONSERVATION OF ENERGY AND THE INCREASE IN DISORDER

1) The total energy of the universe is constant. Energy can be transferred by collisions in chemical and nuclear reactions, by light waves and other radiations, and in many other ways. However, it can never be destroyed. As these transfers occur, the matter involved becomes steadily less ordered. The total energy of the universe is constant. Energy can be transferred by collisions in chemical and nuclear reactions, by light waves and other radiations, and in many other ways. However, it can never be destroyed. As these transfers occur, the matter involved becomes steadily less ordered. (9P.2.2.2.1-3)

2) All energy can be considered to be either kinetic energy, which is the energy of motion; potential energy, which depends on relative position; or energy contained by a field, such as electromagnetic waves. All energy can be considered to be either kinetic energy, which is the energy of motion; potential energy, which depends on relative position; or energy contained by a field, such as electromagnetic waves. (9P.2.2.2.1)

from Benchmarks Online - Project 2061 - AAAS (Physical Setting)

*Energy Transformations (4E):*

4E/H1 - Although the various forms of energy appear very different, each can be measured in a way that makes it possible to keep track of how much of one form is converted into another. Whenever the amount of energy in one place diminishes, the amount in other places or forms increases by the same amount.

4E/H9 - Many forms of energy can be considered to be either kinetic energy, which is the energy of motion or potential energy, which depends on the separation between mutually attracting or repelling objects.

4E/H10 - If no energy is transferred into or out of a system, the total energy of all the different forms in the system will not change, no matter what gradual or violent changes actually occur within the system.

*Motion (4/F):*

4F/H7 - In most familiar situations, frictional forces complicate the description of motion, although the basic principles still apply.

*The Design World - Energy Sources and Use (8C):*

8C/H7 - During any transformation of energy, there is inevitably some dissipation of energy into the environment. In this practical sense, energy gets "used up," even though it is still around somewhere.

**Common Core Standards**

Mathematics: Trigonometry

Momentum, Change in Momentum, and Impulse are vectors. Problems of these sort reinforce the use of vectors and their components in the area of mathematics instruction.

Math standards

(8.1.1.5) Express approximations of very large and very small numbers using scientific notation; understand how calculators display numbers in scientific notation. Multiply and divide numbers expressed in scientific notation, express the answer in scientific notation, using the correct number of significant digits when physical measurements are involved.

For example: (4.2×104)×(8.25×103) =3.465×108 , but if these numbers represent physical measurements, the answer should be expressed as 3.5×108 because the first factor, 4.2×104 , only has two significant digits.

(9.2.1.4) Obtain information and draw conclusions from graphs of functions and other relations.

Students can plot data of force and acceleration to determine the resistance of an object.

(9.2.2.1) Represent and solve problems in various contexts using linear and quadratic functions.

(9.2.2.3) Sketch graphs of linear, quadratic and exponential functions, and translate between graphs, tables and symbolic representations. Know how to use graphing technology to graph these functions.

(9.3.1.3) Understand that quantities associated with physical measurements must be assigned units; apply such units correctly in expressions, equations and problem solutions that involve measurements; and convert between measurement systems.

For example: 60 miles/hour = 60 miles/hour × 5280 feet/mile × 1 hour/3600 seconds = 88 feet/second.

(9.3.1.5) Make reasonable estimates and judgments about the accuracy of values resulting from calculations involving measurements.

For example: Suppose the sides of a rectangle are measured to the nearest tenth of a centimeter at 2.6 cm and 9.8 cm. Because of measurement errors, the width could be as small as 2.55 cm or as large as 2.65 cm, with similar errors for the height. These errors affect calculations. For instance, the actual area of the rectangle could be smaller than 25 cm2 or larger than 26 cm2, even though 2.6 × 9.8 = 25.48.

(9.4.1.3) Use scatterplots to analyze patterns and describe relationships between two variables. Using technology, determine regression lines (line of best fit) and correlation coefficients; use regression lines to make predictions and correlation coefficients to assess the reliability of those predictions.

(9.4.2.3) Design simple experiments and explain the impact of sampling methods, bias and the phrasing of questions asked during data collection.

Minnesota Academic Standards: Language Arts

Anchor Standard | Benchmark |

1. Read closely to determine what the text says explicitly and to make logical inferences from it; cite specific textual evidence when writing or speaking to support conclusions drawn from the text. | 1. Cite specific textual evidence to support analysis of science and technical texts, attending to important distinctions the author makes and to any gaps or inconsistencies in the account. |

2. Determine central ideas or themes of a text and analyze their development; summarize the key supporting details and ideas. | 2. |

3. Analyze how and why individuals, events, and ideas develop and interact over the course of a text. | 3. Follow precisely a complex multistep procedure when carrying out experiments, designing solutions, taking measurements, or performing technical tasks; analyze the specific results based on explanations in the text. |

4. Interpret words and phrases as they are used in a text, including determining technical, connotative, and figurative meanings, and analyze how specific word choices shape meaning or tone. | 4. Determine the meaning of symbols, equations, graphical representations, tabular representations, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to |

5. | 5. Analyze how the text structures information or ideas into categories or hierarchies, demonstrating understanding of the information or ideas. |

6. Assess how point of view or purpose shapes the content and style of a text. | 6. Analyze the author's purpose in describing phenomena, providing an explanation, describing a procedure, or discussing/reporting an experiment in a text, identifying important issues and questions that remain unresolved. |

7. Integrate and evaluate content presented in diverse media and formats, including visually and quantitatively, as well as in words. | 7. Integrate and evaluate multiple sources of information presented in diverse formats and media (e.g., quantitative data, video, multimedia) in order to address a question or solve a problem. |

8. Delineate and evaluate the argument and specific claims in a text, including the validity of the reasoning as well as the relevance and sufficiency of the evidence. | 8. Evaluate the hypotheses, data, analysis, and conclusions in a science or technical text, verifying the data when possible and corroborating or challenging conclusions with other sources of information. |

9. Analyze how two or more texts address similar themes or topics in order to build knowledge or to compare the approaches the authors take. | 9. Synthesize information from a range of sources (e.g., texts, experiments, simulations) into a coherent understanding of a process, phenomenon, or concept, resolving conflicting information when possible. |

10. Read and comprehend complex literary and informational texts independently and proficiently. | 10. |

### Misconceptions

The following misconceptions are taken from (Heller, P, & Stewart, G. (2010). College Ready Physics Standards: A Look to the Future. retrieved on 01/01/2011 from this site.

Several researched based sources for these misconceptions are found in that work.

Students often believe that:

9P.2.2.2.1

1. Energy is confined to a specific origin:

a. Energy is found only in living things (or is what we get from food).

b. Energy is associated only with movement or activity.

c. Energy is only associated with fuels, or what we get from power stations.

2. Energy is a "thing." [This is a fuzzy notion, probably because of the way we talk about Newton meters or joules. It is difficult to imagine an "amount" of an abstraction.]

3. The terms "energy" and "force" are interchangeable.

4. Energies are always the same (mechanical, kinetic, thermal, etc) for all defined systems and time intervals.

5 There are no energy terms for transfer (energy in transit from one location to another) that are different from the energies that objects can have.

6. Work

a. "Work" is synonymous with "labor". It is hard to convince someone that more work is probably being done playing football for one hour than studying an hour for a quiz.

b. A force acting on an object does work even if the object does not move.

c. "Work done on an object" and "work done by an object" does not transfer energy into or out of a system.

7. Doubling the speed of a moving object doubles its kinetic energy.

8. The only type of potential energy is gravitational.

9. Potential energy in not energy. It becomes energy when it is transferred.

10. Gravitational Potential Energy

a. Gravitational potential energy depends only on the height of an object.

b. When an object is released to fall, the gravitational potential energy immediately becomes all kinetic energy.

11. Single Objects Have Potential Energy

a. An object has to stop in order to have potential energy.

b. The potential energy that an object has before it starts moving is more than its kinetic energy at the final stage of motion.

c. Objects always have potential energy. Potential energy is a thing that objects hold (like cereal stored in a closet).

9P.2.2.2.2

12. Circular motion does not require a force.

13. An object moving in circle with constant speed has no acceleration.

14. An object moving in a circle will continue in circular motion when released.

a. A common misconception is that objects will continue to travel in curvilinear paths in the absence of centripetal force. This erroneous view is to similar to the medieval impetus theory as reported in McCloskey et al.'s (1980) study. This impetus theory had the perspective that an object moving through a curved tube (or otherwise forced to travel in a curved path) acquired a "force" or "momentum" that caused it to continue in curvilinear motion for sometimes after emerging from the tube. (McCloskey, M., Caramazza, A., & Green, B. (1980). Curvilinear motion in the absence of external forces: Naïve beliefs about the motion of objects*. Science*, 210(5), 1139-1141.)

15. An object is circular motion will fly out radially when released.

9P.2.2.2.3

16. Momentum is not a vector.

17. Conservation of momentum applies only to collisions.

18. Momentum is the same as force.

19. Moving masses in the absence of gravity do not have momentum.

20. The center of mass of an object must be inside the object.

21. Momentum is not conserved in collisions with "immovable" objects

22. Momentum and kinetic energy are the same concept.

### Vignette

(9P.2.2.2.1) Modeling an Objects Transfer of Gravitational Potential Energy to Kinetic Energy

Mr. Joule has been working with the modeling technique out of Arizona State University for his units on Kinematics and Forces. His students are comfortable with taking data and building relationships through graphing and discovering direct relationships (by linearizing data) to discover the mathematical expressions between variables. The goal of his next lab is to develop energy transfer from gravitational potential energy to the energy of motion, kinetic energy. His students have previously learned from lab experience that the weight of an object in earths gravity field is equal its mass times** g**, a constant found from the slope of the graph by plotting the dependent variable, Weight (N), vs the independent variable mass (kg), constructed from data taken on a spring scale calibrated in Newton's.

At the beginning of this Energy unit Mr. Joule has developed the concept of work or working. See the modeling document on energy for this description (this page) and the idea of energy exchange. They have formulated the idea that gravitational potential energy mgΔh can be transferred. Today's lab is meant to establish that energy can be transferred by a change in gravitational potential energy to kinetic energy. Eight stations of ramps are set up around the room with carts on them and a photogate is arranged near the bottom to measure the speed of the cart as it passes through. Each station has a different amount of mass on the cart so that each groups data is unique.

The students let the carts go from the same initial height each time calculating and recording the change in the carts gravitational potential energy as it has passed through the photogate. They also record the speed of the cart as given by the photogate. The location of the photogate is changed to vary the change in height for 8 subsequent trials. Each group calculates and plots the transfer of gravitational potential energy ΔPEgrav (J) on the y-axis and the carts speed v (m/s) on the x-axis for each trial. Finding an upwards opening parabola the students must then linearize their data to find a direct relationship and plot the gravitational potential energy transferred (J) vs v^{2 }(m^{2}/s^{2}), the square of the speed. Upon whiteboarding their results, and sharing their found linear equations, they discover through Socratic Dialogue with the teacher that the slope of the graphs are equal to ½ the mass of the carts for every groups resulting slope. By writing the equation ΔPEgrav=1/2mv^{2} and analyzing the units of ΔPEgrav and ½ mv^{2} the students have a mathematical formula and conceptual framework for understanding the transfer of gravitational potential energy to kinetic energy. This lab is followed up the next day with the students using the PHET simulation *Energy** **Skate** **Park* and learning about energy conservation while viewing energy bar charts and graphs about Potential Energy, Kinetic Energy, and Total Mechanical Energy.

*The above vignette can be combined with the following or either one or used instead of the other.*

*The following vignette was graciously provided by Michael Crofton from Spring Lake Park High School who is recognized as an expert modeler in teaching physics.*

Vignette Option 2

Preliminary Investigation: Determine the relationship of the force applied to a spring and the distance the spring stretches

Begin by doing a lab where students determine the relationship of the force applied to a spring and the distance the spring stretches. Students gather their data and graph it on the computer. After that lab the students share their results on whiteboards. They have to figure out why the graphs have different slopes. After examining different springs used in the lab they notice that the springs with larger slopes are more difficult to stretch. They come to the conclusion that the slope of the graph has something to do with how strong the spring is. We then name the slope the spring constant and give it the variable "k". In further discussion they are asked what the spring might contain after it was stretched that was not there before it was stretched. Usually someone says energy. Tell them the unit of energy is the newton meter and ask them how they could use their graph to get a quantity with this unit. From their study of motion students are familiar with obtaining values using the area of a graph. Therefore it is not surprising for a student to propose the area of the spring graph would give us newton meters. I relay to the students that yes, the area of a force position graph is called the work or the energy transferred. We go about analyzing the area of the spring graph and notice that Fx/2 can also be calculated as ½ kx2. We name this energy account elastic potential energy. We now are ready to do an investigation of energy.

Primary Investigation : Determine the relationship of the energy stored in a spring and the velocity of a cart.

In this investigation the students hook a spring to a cart, pull the cart back to stretch the spring and let go. After the spring has pulled the cart and has no tension in it, the cart goes through a photogate where the time for a flag to pass through the photogate beam is measured by the computer.

Students then calculate the energy stored in the spring before release and the velocity of the cart at the end. Next they graph energy vs. velocity and get a top opening parabola. Students have learned that to linearize a top opening parabola they need to square the x-variable, in this case the velocity. This produces a linear graph so the students are now able to write an equation for the lab and state the relationship. Their statement is the energy is proportional to the square of the velocity. After they write the equation they then try to determine what the slope represents. By this lab students have become adept at doing this. When they simplify the units of the slope they find the units simplify to kg. They look at their lab and realize that they kept the mass of the cart constant and it was measured in kg. It's a little tricky but with a bit of thinking they usually come up with the slope being one half the mass of the cart. They now have the general equation E = 1/2mv^{2}.

The next step in the process is for the students to place what they found out in the lab on a whiteboard. (There is an example of a completed whiteboard for this lab in the pictures.) They get their thoughts together as they make the whiteboard and then present the board to their classmates. The teacher's job in this presentation is to assist them by asking questions if they have not figured out everything, and to put names to what they have discovered. In this lab I ask the students, "Where is the energy that started out in the spring?" When they reply in the moving car, I tell them that we call the energy account for moving objects is called kinetic energy. To check for their understanding I ask them how could they do the lab again and get a different slope. Would this change make the slope larger or smaller? In the lab setup each group was given a cart with a different mass and students had springs of two different strengths. The springs made no difference in the slope and the mass of the cart was twice the slope no matter what the mass was.

Columbia Shuttle disaster impact test by NASA

### Resources

**Suggested Labs and Activities**

Lab Investigations

Vernier Investigations:

Vernier technology is a source of data collection that allows students to accurately predict and analysis data. The links below are the complete labs as posted by Vernier Software and Technology.

Energy in Simple Harmonic Motion - Examine the energies involved with springs and test the principle of conservation of energy. (9P.2.2.2.1)

Energy of a Tossed Ball - Measure the change in kinetic and potential energies of a free falling ball. Examine the total energy of the ball during free fall. (9P.2.2.2.1)

Impulse and Momentum - Measure a cart's momentum change and compare to the impulse it receives. (9P.2.2.2.3)

Momentum, Energy and Collisions - Examine the conservation of momentum and change in kinetic energy during two chart collisions. Classify three collisions as elastic, inelastic, or completely inelastic. (9P.2.2.2.1, 9P.2.2.2.3)

Impulsive Juggling - Use video of a juggler's hand and ball to verify the impulse momentum theorem in a typical catch-throw process. (9P.2.2.2.3)

Net Work-Kinetic Energy Theorem - Verify the Work-Kinetic Theorem through video of a low-friction cart being pulled on a track. (9P.2.2.2.1)

Pasco "Exploration in Physics" Curriculum

Activity 9 - Conservation of Momentum-Inelastic Collision (9P.2.2.2.3)

PDF (560 KB) Investigate the momentum of two carts before and after they collide.

Activity 10 - Conservation of Energy-GPE and KE (9P.2.2.2.1)

PDF (584 KB) Investigate the relationship between the change in the gravitational potential energy and the kinetic energy of a falling object.

Activity 11 - Impulse and Change in Momentum-Collision (9P.2.2.2.3**)**

PDF (748 K) Investigate the change in momentum and the impulse in a collision.

Activity 12 - Projectile Motion-Initial Speed and Time of Flight (9P.2.2.2.1)

PDF (508 KB) Compare the time of flight of a projectile for different values of initial speed when the projectile is aimed horizontally.

Activity 13A - Circular Motion-Centripetal Force (Part 1) (9P.2.2.2.2)

PDF (544 KB) Explore the relationship of centripetal force and circular speed when radius and force are constant.

Activity 13B - Circular Motion-Centripetal Force (Part 2) (9P.2.2.2.2)

PDF (548 KB) mass and force are constant.

Activity 13C - Circular Motion-Centripetal Force (Part 3) (9P.2.2.2.2)

PDF (564 KB) Explore the relationship of centripetal force, circular speed, and radius when mass and force are constant.

*Activities*

Student Practicum Problems:

*Practicums For Physics Teachers* (Ryan, Henry and Barber, Jon, 2008)

Two high school teachers developed practicums for students to solve problems using an understanding of physics concepts and critical thinking skills. The booklet of labs are sold directly by the authors, and cannot be found in book stores or on-line. A link to the order form is listed here.

Spring Potential Energy (p. 68) - Predict the time measured on a photo-gate timer for the run of a spring launched bumper sled. (9P.2.2.2.1)

Humpty Dumpty (p. 71) - Place an egg under a suspended mass that, when released, stretches a spring as it falls, so that the egg is just touched or cracked, but not smashed. (9P.2.2.2.1)

Ballistic Pendulum (p. 74) - Predict the distance a projectile will travel when shot horizontally from a ballistic pendulum. (9P.2.2.2.1 and 9P.2.2.2.2)

Jumping Frame (p. 77) - Predict how far and which direction, a frame will move when the enclosed cars explode apart. (9P.2.2.2.3)

Tarzan (p. 80) - A pendulum bob swings down through an arc, at the very bottom of the swing a razor blade cuts the bob free, determine the point of impact of the bob with the floor. (9P.2.2.2.2 and 9P.2.2.2.3)

Vector Conservation of Momentum (p. 82) - When a ball is released down an acceleration ramp, and no collision with a second ball occurs, where will the ball land on the floor? (9P.2.2.2.2 and 9P.2.2.2.3)

Gravitational Potential Energy (p. 85) - Calculate where a puck will hit the floor after it is pulled to the edge of an air table by falling weights. (9P.2.2.2.2 and 9P.2.2.2.3)

Kinetic Energy of the foam piece that struck the wing of Columbia in Feb. 2003 (9P.2.2.2.1)

Worksheets

(9P2.2.2.1)

These are ready made worksheets to use for energy concepts getting at both mathematical and conceptual development.

(9P.2.2.2.3)

These are ready made worksheets to use for impulse, momentum, and momentum conservation getting at both mathematical and conceptual development.

Impulse, Momentum, Conservation Worksheets

**Instructional Suggestions/Options**

(9P.2.2.2.1, 9P.2.2.2.2, 9P.2.2.2.3)

Modeling Physics Resources in Motion at Arizona State University

The Modeling Instruction Program is dedicated to

Research-based reform of physics instruction at all grade levels

Sustained professional growth and support for physics teachers

This page serves as a portal to various components of the program. The approach to reform of curriculum design and teaching methodology has been guided by a *Modeling Theory of Physics Instruction*, the focus of educational research by** **David Hestenes and collaborators since 1980. Implementation through Modeling Workshops** **for high school teachers was supported by grants from the National Science Foundation from 1989 to 2005. The documented success of workshops and the enthusiastic response of teachers has stimulated institutionalization and expansion of the program through increased involvement of university physics departments.

*Physics Quests from Delores Gende*

A WebQuest, according to Bernie Dodge, the originator of the WebQuest concept from San Diego State University, "is an inquiry-oriented activity in which most or all of the information used by learners is drawn from the Web. WebQuests are designed to use learners' time well, to focus on using information rather than on looking for it, and to support learners' thinking at the levels of analysis, synthesis, and evaluation.

CONSERVATION OF MOMENTUM (9P.2.2.2.3)

CONSERVATION OF ENERGY (9P.2.2.2.3)

Videos to learn how to implement the National Standards using Inquiry Techniques from the Annenburg Foundation

To be viewed together here.

**1. ***Introduction*

Classroom footage and new footage of scientists in the field explain and illustrate the concept of inquiry.

**Additional Resources**

*The Physics Classroom*:** ** Resource for both teachers and students. Website is sectioned into Read/Watch/Interact, Practice/Review, and Teacher Tools.

Readings:

Concepts of work, kinetic energy and potential energy are discussed; these concepts are combined with the work-energy theorem to provide a convenient means of analyzing an object or system of objects moving between an initial and final state. (9P.2.2.2.1)

Circular Motion and Satellite Motion

Newton's laws of motion and kinematic principles are applied to describe and explain the motion of objects moving in circles; specific applications are made to roller coasters and athletics. Newton's Universal Law of Gravitation is then presented and utilized to explain the circular and elliptical motion of planets and satellites. (9P.2.2.2.1)

The impulse-momentum change theorem and the law of conservation of momentum are introduced, explained and applied to the analysis of collisions of objects. (9P.2.2.2.3)

*123Physics:* Regents Review Questions, Physics Lessons, Videos, and Physics Clipart

ComPADRE is filling a stewardship role within the National Science Digital Library for the educational resources used by broad communities in physics and astronomy. This partnership of the American Association of Physics Teachers (AAPT), the American Astronomical Society (AAS), the American Institute of Physics/Society of Physics Students (AIP/SPS), and the American Physical Society (APS) helps teachers and learners find, and use, high quality resources through collections and services tailored to their specific needs.

The Physics Front provides high quality resources for the teaching of physics and physical sciences courses. You may search or browse the Physics Front in order to find materials appropriate for your physics classes. Additionally, registering will allow you to share your experiences using materials. The Physics Front is a free service provided by the American Association of Physics Teachers in partnership with the NSF/NSDL.

Physics Win or Physics Fail?

Use your knowledge of physics to put these videos to the test!

Inspired by Rhett Allain's physics explanations at Dot Physics, Dan Meyer's blog series "What Can You Do With This?", and Dan's TEDx plea for a math curriculum makeover, I have been collecting video clips that are prime for my physics students to analyze.

Videos are categorized by topic to help teachers locate videos for the concepts at hand. Several videos are listed under multiple topics. The videos are presented without any further questions other than "Physics win or physics fail?" (real or fake?)

If you are looking around for some good labs to use or to tweek, check this site out. Items have been put here for physics teachers, by physics teachers, and range from first-year high school physics to AP material. The emphasis is on labs, but explanatory material is also available. The University sources on the bottom will direct you to even more great material. The collection of materials is growing all of the time.

**Vocabulary/Glossary**

**Centrifugal Force:**an apparent outward force on an object following a circular path. This force is a consequence of the third law of motion.**Centripetal Force:**the force required to pull an object out of its natural straight-line path and into a circular path.**Conservation of Energy:**a principle stating that the total energy of an isolated system remains constant regardless of changes within the system.**Conservation of Mechanical Energy:**mechanical energy is the kinetic energy plus all of the kinds of potential energy that are present. In the absence of non-conservative forces, mechanical energy is conserved, meaning that it remains constant within a system (just changing its forms).**Conservation of Momentum:**the principle that the total linear momentum in a closed system is constant and is not affected by processes occurring inside the system.**Conservative Force:**a force with the property that the work done in moving a particle between two points is independent of the path taken, such as gravity.**Elastic Collision:**an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter.**Elastic Potential Energy:**the energy a spring possesses due its stretched or compressed position.**Energy Conversion:**the transfer of energy between forms.**Gravitational Potential Energy:**the energy an object has due to its location in a gravity field.**Inelastic Collision:**a collision between two or more bodies in which kinetic energy is not conserved.**Kinetic Energy:**the energy an object has due to its motion; it is equal to ½ mv^{2}, where m is the mass and v is the speed of the body.Work: work is done when a force acting on a body displaces it. Work = Force component parallel to the displacement x Displacement. W=Fdcos[?][?]**Net Work:**algebraic sum of the work done by all of the forces acting to displace an object.**Non-Conservative Force:**a force with the property that the work done in moving a particle between two points is independent of the path taken, such as friction.**Potential Energy:**the energy an object has due to its location in a force field.**Power:**the rate of doing work.**Work Kinetic Energy Theorem:**Net Work done on a body equals the change in its Kinetic Energy.

Center for Orbital and Reentry Debris Studies

Web Based Simulations:

*University of Colorado PhET Simulations*

Each of the following simulations allow students to work with and visualize various configurations of gravitational or elastic potential energy and kinetic energy conversions as a powerful supplement to real world experimentation. Students may interact with and vary the physical parameters of the simulations and view energy bar or pie chart diagrams. Transfers of energy to heat can be used and accounted for in the models. Many of the simulations allow students to visualize and engage with phenomena that cannot be done in the high school lab setting. All of these simulations have accompanying lesson plans, student documents, and teacher resources developed by teachers for you to use in your classroom.

*Energy Skate Park Simulation at University of Colorado Boulder PHET (**9P.2.2.2.1)*

Learn about conservation of energy with a skater dude! Build tracks, ramps and jumps for the skater and view the kinetic energy, potential energy and friction as he moves. You can also take the skater to different planets or even space! See this page.

*Masses and Springs Simulation at University of Colorado Boulder PHET*

A realistic mass and spring laboratory. Hang masses from springs and adjust the spring stiffness and damping. You can even slow time. Transport the lab to different planets. A chart shows the kinetic, potential, and thermal energy for each spring.

*The Ramp Energy and Force Simulation at University of Colorado Boulder PHET *(9P.2.2.2.1)

Explore forces, energy and work as you push household objects up and down a ramp. Lower and raise the ramp to see how the angle of inclination affects the parallel forces acting on the file cabinet. Graphs show forces, energy and work.

*Rotation Simulation at University of Colorado Boulder PHET (**9P.2.2.2.2)*

Join the ladybug in an exploration of rotational motion. Rotate the merry-go-round to change its angle, or choose a constant angular velocity or angular acceleration. Explore how circular motion relates to the bug's x,y position, velocity, and acceleration using vectors or graphs.

*The Collision Lab Simulation at University of Colorado Boulder PHET*** **(9P.2.2.2.3)

Investigate collisions on an air hockey table. Set up your own experiments: vary the number of discs, masses and initial conditions. Is momentum conserved? Is kinetic energy conserved? Vary the elasticity and see what happens.

*Multimedia Physics Studio*

Energy animations for conceptual development (9P.2.2.2.1)

Momentum and Collisions animations for conceptual development (9P.2.2.2.3)

*Web Based Instructional Videos:*

T*he Annenburg Foundation's Mechanical Universe Collection Video on Demand*

This series helps teachers demystify physics by showing students what it looks like. Field trips to hot-air balloon events, symphony concerts, bicycle shops, and other locales make complex concepts more accessible. Inventive computer graphics illustrate abstract concepts such as time, force, and capacitance, while historical reenactments of the studies of Newton, Leibniz, Maxwell, and others trace the evolution of theories. *The Mechanical Universe* helps meet different students' needs, from the basic requirements of liberal arts students to the rigorous demands of science and engineering majors. This series is also valuable for teacher professional development.

13. Conservation of Energy (9P.2.2.2.1)

According to one of the major laws of physics, energy is neither created nor destroyed.

14. Potential Energy (9P.2.2.2.1)

Potential energy provides a powerful model for understanding why the world has worked the same way since the beginning of time.

15. Conservation of Momentum (9P.2.2.2.3)

What keeps the universe ticking away until the end of time?

*Hippocampus*

HippoCampus is a project of the Monterey Institute for Technology and Education (MITE). The goal of HippoCampus is to provide high-quality, multimedia content on general education subjects to high school and college students free of charge. This site could be used in conjuction with your course to help teach the standards at various levels.

(9P.2.2.2.1) Work Energy and Power

(9P.2.2.2.2) Circular Motion and Rotation

(9P.2.2.2.3) Linear Momentum and Conservation

Use your knowledge of physics to put these videos to the test!

Inspired by Rhett Allain's physics explanations at Dot Physics, Dan Meyer's blog series "What Can You Do With This?", and Dan's TEDx plea for a math curriculum makeover, I have been collecting video clips that are prime for my physics students to analyze.

Videos are categorized by topic to help teachers locate videos for the concepts at hand. Several videos are listed under multiple topics. The videos are presented without any further questions other than "Physics win or physics fail?" (real or fake?)

For Teachers:

(9P.2.2.2.1) *The Annenburg Foundation's Science in Focus: Energy Video on Demand *

Driver Education

1. Stopping Distance - understanding the relationship between work and kinetic energy.

2. Importance of air bags - understanding the relationship between change in momentum and impulse.

Videos to support Car Crash Physics

"Crash" - Science of Collisions (includes curriculum for biology, physics, and Math

**Physical Education**

1. Energy use and efficiency of the human body during physical exercise

2. Power developed and Energy usage by the human body

### Assessment

**Assessment of Students**

The following good conceptual multiple choice questions with answers are found at The Physics Classroom.com. Perfect for review or use on tests.

*Work, Energy, and Power (*9P.2.2.2.1)

Description: Questions pertain to the analysis of motion using relationships related to work and energy, mainly energy conservation and work-energy transfer principles. The following concepts are emphasized: work, positive work, negative work, energy, power, conservative (internal) forces, non-conservative (external) forces, potential energy, kinetic energy, mechanical energy, conservation of energy, work-energy theorem, pendulum, and incline planes.

*Momentum and Collisions (*9P.2.2.2.3)

Description: Questions pertain to the application of the momentum change-impulse theorem and the momentum conservation principle to the analysis of collisions and explosions. Some problems involve combining a momentum analysis with kinematic equations or work-energy theorem. Some elastic collisions problems presume a prior knowledge of kinetic energy. Some problems involving two-dimensional collisions require a vector analysis. The following concepts are emphasized: momentum, impulse, momentum change-impulse theorem, action-reaction, momentum conservation, momentum transfer, two-dimensional collisions, momentum vectors, inelastic collisions, elastic collisions, glancing collisions, Pythagorean theorem, and SOHCAHTOA.

(9P.2.2.2.1) Question #1: Harrington, R, & Keeley, P. (2010). *Understanding student ideas in physical science, vol. 1*. NSTA Press.

Rachel is wearing roller skates and is standing next to a wall. She pushes off from the wall and then glides to a stop. Place an X next to all the statements that you think are true about Rachel's motion.

____ A The force from the wall is becoming less and less as Rachel glides on her skates.

____ B Rachel's motion energy is naturally going down and the energy is disappearing.

____ C Rachel's motion energy is being turned into other types of energy.

____ D There is a force by the ground slowing Rachel down.

____ E There is a force by the ground that keeps Rachel moving for a while before she stops.

Explain your thinking about why Rachel slowed down and stopped after pushing off from the wall.

*Answer: Best two answers are C and D.*

(9P.2.2.2.1) Question #2:

A 2.0 kg object starting from rest and 10 m above the ground, slides down a 25 degree ramp, reaching the bottom with a speed of 10 m/s. What is the approximate work done by friction?

A) 0 J B) 16 J C) - 50 J D) - 100 J E) - 200J

*Answer: D) -100 J*

(9P.2.2.2.1) Question #3:

Which of the following four bodies has the greatest kinetic energy?

a. A body of mass 1 kg moving with speed 1 m/s.

b. A body of mass 2 kg moving with speed 5 m/s.

c. A body of mass 3 kg moving with speed 50 m/s.

d. A body of mass 5 kg moving with speed 10 m/s.

e. A body of mass 5 kg moving with speed 100 m/s

*Answer E.*

(9P.2.2.2.2) Question #4:

Problem 1: A curved tube is placed horizontally on a table. A ball is put in the end indicated by the arrow and shot out at high speed.

Problem 2: Two thin curved metal tubes are placed horizontally. A small metal ball is put into the end of each of the tubes indicated by the arrows. The balls are then shot out of the other ends of the tubes at high speed.

For both cases draw the paths the balls will follow immediately after they come out of the tube.

(9P.2.2.2.2) Question #5:

A metal ball attached to a string and is traveling at a constant speed in a *horizontal circle *in a clockwise direction In Figure 2 you are looking down on the ball. The line from the center of the circle to the ball is the string. Assume that when the ball is at the point P, the string suddenly breaks. Ignoring air resistance, Which path does the ball take immediately after the string breaks?

Explain why the ball moves in the path drawn by you.

(9P.2.2.2.2) Question 6.** **An object moving at a constant speed requires 6.0 s to go once around a circle with a diameter of 4.0 m. What is the magnitude of the instantaneous acceleration of the particle during this time?

**a.** 2.2 m/s^{2}

**b.** 3.7 m/s^{2}

**c.** 4.3 m/s^{2}

**d.** 4.8 m/s^{2}

**e.** 5.9 m/s^{2}

Answer A.

(9P.2.2.2.3) Question 7. Two boys in a canoe toss a baseball back and forth. What effect will this have on the canoe?

**a.** None, because the ball remains in the canoe.

**b.** The canoe will drift in the direction of the boy who throws the ball harder each time.

**c.** The canoe will drift in the direction of the boy who throws the ball with less force each time.

**d.** The canoe will oscillate back and forth always moving opposite to the ball.

**e.** The canoe will oscillate in the direction of the ball because the canoe and ball exert forces in opposite directions upon the person throwing the ball.

Answer D.

(9P.2.2.2.3) Question 8. A 2.0-kg object moving 5.0 m/s collides with and sticks to an 8.0-kg object initially at rest. Determine the percent kinetic energy lost by the system as a result of this collision.

**a.** 0 %

**b.** 15 %

**c.** 50 %

**d.** 80 %

**e.** 100 %

Answer D

1) How can you best describe the conceptual difference between an objects momentum and kinetic energy to a student? its affects on a collision event?

(9P.2.2.2.1) question 9. Suppose a ping-pong ball and a bowling ball are rolling toward you. Both have the same momentum, and you exert the same force to stop each. How do the distances needed to stop them compare?

A. It takes a shorter distance to stop the ping-pong ball.

B. Both take the same distance.

C. It takes a longer distance to stop the ping-pong ball.

Answer C

(9P.2.2.2.3) 10. Suppose rain falls vertically into an open cart rolling along a straight horizontal track with negligible friction. As a result of the accumulating water, the speed of the cart

A. increases.

B. does not change.

C. decreases.

Answer C

(9P.2.2.2.1) 11. Two marbles, one twice as heavy as the other, are dropped to the ground from the roof of a building. Just before hitting the ground, the heavier marble has

A. as much kinetic energy as the lighter one.

B. twice as much kinetic energy as the lighter one.

C. half as much kinetic energy as the lighter one.

D. four times as much kinetic energy as the lighter one.

E. impossible to determine.

Answer B

(9P.2.2.2.3) 12. Consider these situations:

(*i*) a ball moving at speed v is brought to rest;

(*ii*) the same ball is projected from rest so that it moves at speed v;

(*iii*) the same ball moving at speed v is brought to rest and then projected

backward to its original speed.

In which case(s) does the ball undergo the largest change in momentum?

A. (*i*)

B. (*i*) and (*ii*)

C. (*i*), (*ii*), and (*iii*)

D. (*ii*)

E. (*ii*) and (*iii*)

F. (*iii*)

answer F

2) *Peer Instruction: A User's Manual*, (Mazur, Eric, Harvard University, Prentice Hall, 1997) - strategies and conceptual questions for using Student Response Systems.

Forces

CT6: Force on a car traveling on a curved road (9P.2.2.2.2)

CT10: Force on a person in a car making a sharp turn (9P.2.2.2.2)

Work and Energy

CT2: kinetic energy of dropped objects (9P.2.2.2.1)

CT4: Force and work lifting an object with pulleys (9P.2.2.2.1)

CT5: Force and work lifting an object with pulleys (9P.2.2.2.1)

CT6: kinetic energy of an object sliding down a ramp (9P.2.2.2.1)

Gravitation

CT2: Centripetal force on a object in orbit (9P.2.2.2.2)

CT3: Centripetal force on a object in orbit (9P.2.2.2.2)

CT4: Centripetal force on a object in orbit (9P.2.2.2.2)

CT6: Force of Earth's gravity on Moon (9P.2.2.2.2)

Inertial Mass, Collisions, Momentum

CT1: Inertial mass of object in space (9P.2.2.2.2)

CT2: Collision of two cars (9P.2.2.2.3)

CT4: Momentum of car moving on Earth (9P.2.2.2.3)

CT8: Momentum of moving truck in rain storm (9P.2.2.2.3)

CT10: Change of momentum for ball slowing down (9P.2.2.2.3)

CT11: Momentum change for two different cars (9P.2.2.2.3)

CT14: Momentum of ping pong ball and bowling ball (9P.2.2.2.3)

CT15: Momentum and Newton's Cradle (9P.2.2.2.3)

CT18: Head on Collision with car compared with colliding wall (9P.2.2.2.3)

CT20: Inelastic collision of car with wall (9P.2.2.2.3)

CT21: Collision of car with truck (9P.2.2.2.3)

CT23: Momentum gained by throwing balls at a wall (9P.2.2.2.3)

**Assessment of Teachers **

Questions could be used as self-reflection or in professional development sessions.

Modeling Instruction in High School Physics, Chemistry, Physical Science, and Biology

Materials and readings for teacher discussion and use for professional development

The Modeling Method of High School Physics Instruction has been under development at Arizona State University since 1990 under the leadership of David Hestenes, Professor of Physics. The program cultivates physics teachers as school experts on effective use of guided inquiry in science teaching, thereby providing schools and school districts with a valuable resource for broader reform. Program goals are fully aligned with National Science Education Standards. The Modeling Method corrects many weaknesses of the traditional lecture-demonstration method, including fragmentation of knowledge, student passivity, and persistence of naive beliefs about the physical world. Unlike the traditional approach, in which students wade through an endless stream of seemingly unrelated topics, the Modeling Method organizes the course around a small number of scientific models, thus making the course coherent. In 2000 the program was extended to physical science and in 2005 to chemistry, by demand of committed teachers. See this page.

*Peer Instruction: A User's Manual*, (Mazur, Eric, Harvard University, Prentice Hall, 1997) - strategies and conceptual questions for using Student Response Systems.

Forces

CT6: Force on a car traveling on a curved road (9P.2.2.2.2)

CT10: Force on a person in a car making a sharp turn (9P.2.2.2.2)

Work and Energy

CT2: kinetic energy of dropped objects (9P.2.2.2.1)

CT4: Force and work lifting an object with pulleys (9P.2.2.2.1)

CT5: Force and work lifting an object with pulleys (9P.2.2.2.1)

CT6: kinetic energy of an object sliding down a ramp (9P.2.2.2.1)

Gravitation

CT2: Centripetal force on a object in orbit (9P.2.2.2.2)

CT3: Centripetal force on a object in orbit (9P.2.2.2.2)

CT4: Centripetal force on a object in orbit (9P.2.2.2.2)

CT6: Force of Earth's gravity on Moon (9P.2.2.2.2)

Inertial Mass, Collisions, Momentum

CT1: Inertial mass of object in space (9P.2.2.2.2)

CT2: Collision of two cars (9P.2.2.2.3)

CT4: Momentum of car moving on Earth (9P.2.2.2.3)

CT8: Momentum of moving truck in rain storm (9P.2.2.2.3)

CT10: Change of momentum for ball slowing down (9P.2.2.2.3)

CT11: Momentum change for two different cars (9P.2.2.2.3)

CT14: Momentum of ping pong ball and bowling ball (9P.2.2.2.3)

CT15: Momentum and Newton's Cradle (9P.2.2.2.3)

CT18: Head on Collision with car compared with colliding wall (9P.2.2.2.3)

CT20: Inelastic collision of car with wall (9P.2.2.2.3)

CT21: Collision of car with truck (9P.2.2.2.3)

CT23: Momentum gained by throwing balls at a wall (9P.2.2.2.3)

### Differentiation

Strategies from *The Inclusive Classroom: Teaching Mathematics and Science to English-Language Learners ,* (Jarrett, Denise, Northwest Regional Educational Laboratory, Nov. 1999)

Thematic Instruction: Theme-based units can help ELL students connect prior knowledge to language and real-world applications.

Cooperative Learning: Students use language related to task, while conversing and tutoring one another.

Inquiry and Problem Solving: Inquiry and problem solving can be used prior to proficiency in English. Inquiry approaches in science can help student's language acquisition as well as their content knowledge.

Vocabulary Development: Students learn the meaning of words best during investigations and activities, instead of as a vocabulary list.

Modify Speech: Teachers can help ELL students by using an active voice, limiting new terms, using visual support, and paraphrasing or repeating difficult concepts. Slowing down speech, speaking clearly, and using a simple language structure will help ELL students with understanding.

Make ELL Students Feel Welcome: Encourage ELL students to express ideas, thought, and experiences. Focus on what student is say, not how they say it.

Book: * **Science Education for Gifted Students: A Gifted Child Today Reader* (Johnsen, S. K. and Kendrick, J., 2005, Prufrock Press, Inc.)

### Parents/Admin

**Administrators**

If observing a lesson on this standard what might they expect to see.

Ideas adapted from *Best Practice: Today's Standards for Teaching and Learning in America's Schools* (Daniels, H, Hyde, A, and Zemelman, S, Heinemann, Portsmouth, NH, 2005).

1) Students being challenged in thinking how energy and/or momentum is conserved.

2) Students testing their understanding of energy and momentum with investigations or solving real life scenarios using the concepts and associated equations.

3) Students taking on responsibility for their own learning.

4) Student working in collaborative groups, analyzing, synthesizing, and defending conclusions.

5) Students sharing explanations for results of investigation and understanding of concepts.

6) Students continuously assessing and being assessed on their understanding of work, power, energy and momentum concepts.

7) Students concepts are being built on prior knowledge of motion, such as vector forces, velocity, acceleration, weight and mass.