Dr. Alan J. Scott

List of Contents: 

Abstract Describing Animations 

Construction Methods

Suggested Guidelines for Using the Animations

Mechanics Atwood Machine, Carnot Cycle, Stress/Strain, Central Force Orbits Electromagnetism and Waves Doppler Effect, Charged Particle in a Magnetic Field, Faraday's law of Electromagnetic Induction, Bohr Atom, Multiple Lenses, He-Ne Laser, Multiple Slit Diffraction, Planck Curve Geophysics Earthquake Waves, Excavation Safety, Soil Compression, Soil Consolidation, Geological Time, Hydrograph Astronomy Phases of the Moon, Kepler's Laws, Central Force Orbits, Relativity, Sun's Life Cycle, Tidal Forces, Journey Into The Sun, Heliocentric Worldview, Geocentric Worldview General Physical Science CAT Scan, Quantum Mechanical Non-locality

Other Physical Science Video/Animations On The Web

Students in introductory science classes often have difficulty in conceptualizing the time evolution of physical systems. In other words, they have difficulty with concepts that involve motion. These animations are designed to provide an additional instructional mode to help students gain an understanding of how certain systems evolve with time. An activity or question has been incorporated into each animation which require students to apply the concepts.

The animations can be used in many ways. Some of these include self-paced study via the web, multi-media instructional resource - animations or colored transparencies, and using them as part of student assignments. This document outlines how the animations were constructed and suggests ways they can be fully utilized to improve learning.

The first step in developing these animations was to choose a topic that was ideally suited for animations. An example of this is the motion of a charged particle in a magnetic field. Moving charged particles cannot be seen directly with the naked eye and they usually move at speeds that seem instantaneous to human perception. By animating the particle and viewing it in slowed down motion, students can begin to appreciate its behavior and still apply physical concepts to predict its trajectory.

The faculty were also surveyed to find out which physical concepts they felt could be most effectively demonstrated with an animation. Table 1 lists the result of this survey. The high priority topics were assigned a value of 3 and low priority a 1. Five faculty responded to the survey. The top 13 out of 66 topics are listed.

Table 1

I used the results of this survey, together with some topics of personal interest in my teaching, to decide upon a list of animations.

After the topics were chosen, they were reviewed in the literature. Style and content for the animations were selected. Technical accuracy was maintained whenever possible during the construction of the animations.

For most of the development two software programs were used. One of these being Canvas version 5.0.3. Canvas is an object oriented, integrated graphics environment. It lets you work with drawings, images, type, and import graphics. It also has many software tools for designing unique graphics. The software can output and input a large variety of formats. For further information see the web home page for the Deneba software company.

Each animation was constructed frame-by-frame. This required each frame of the movie to originally come from a TIF file. Each TIF file came from a CANVAS format graphics file that was exported as a TIF file. This needed to be done because the movie software was not compatible with CANVAS or GIF formats but was compatible with TIF formatted files. Some of the animations consisted of about 100 files (or frames) with the average TIF file requiring ~400kbytes of disk space. The average CANVAS file format was ~500 kbytes in size. This did consume a considerable amount of time constructing each file, but moving objects around inside of Canvas was relatively easy. The graphics environment can be displayed with a distance grid of the users desired scaling.

Once the frames were constructed they needed to be compiled into a movie format such as AVI (Windows) or MOV (QuickTime). This was done using Adobe Premier which is a video, audio, and/or still frame editing software package. This software has a wide range of movie making tools. Some of the tools included pre-packaged transitions between still frames, regulating the duration of each frame, controlling the number of frames presented per second, and video compression to minimize the computer requirements for playing the movies. A video quality movie would require about 30 frames per second. It is important to note that a 2 minute long animation, presented at 30 frames per second with each frame about 400 kbytes in size soon becomes unmanageable with a size of 1,440 Mbytes without compression of some sort.

Two of each of the animations have been constructed. One set of the animations was purposely kept small in size so they can be readily presented via the World Wide Web. This was done by selecting only 2 frames per second to be presented during play. Thus, making the movies smaller in size. These smaller sized animations contain the same content and are the same duration as the larger sized animations. Their average size was about 2 Mbytes. The quality of the transitions between frames is the sacrifice necessary to keep the animation small in size. The large size animations have 15 frames per second and average 9 Mbytes in size (or about 3.5 times larger than the smaller size animations). These are intended to be used with a CD ROM disk or to be maintained on the Hard Drive of the computer presenting the animation.

These animations have been optimized in AVI format. QuickTime (mov) format can also be developed for all the animations.

1. Newton's Laws of Motion and the Atwood Machine (2.2 Mb, AVI format, compressed - 1 Mb)

This animation applies many concepts. The most important being Newton's 2nd Law. Other concepts include weight and gravity, friction, tension, and inclined planes. The frames showing breaking the weight into its components, force of friction, tension, and problem solving technique can be used as transparencies to discuss these topics. The animation can be shown illustrating the subsequent movement based upon the given conditions. The students can be ask to calculate/predict the movement of the blocks in the exercise part of the animation. They can compare their results with how it does move. This diagram can also be used as a template where the instructor can change the parameters and have students determine the system's behavior.

2. Bohr Atom (1.0 Mb, AVI format, compressed - 0.4 Mb)

The Bohr atom is a simplified view of the true nature of the atom. It's pedagogical strength is that it can be easily conceptualized and that it correctly predicts the emission lines of the hydrogen atom. Thus, one could argue that the model has a certain degree of accuracy. A correct description involves solutions to the Shrodinger equation and describing the motion and position of the electron with a probability distribution. The first part of this animation presents the fundamentals of the Bohr theory. The exercise has the student calculating the wavelength of light emitted for a particular energy transition. Students can also be questioned about any other transitions by modifying the "base" template. The presentation should include a discussion of energy diagrams, absorption, and emission. A common point of confusion is distinguishing this emission spectrum from the Black-Body Curve spectrum. The instructor should emphasize the latter is a continuous spectrum emitted from a solid (usually solid) at a given temperature.

3. Carnot Cycle and the Ideal Heat Engine (2.9 Mb, AVI format, compressed - 1.2 Mb)

The efficiency of heat engines are defined as the amount of usable energy that can be obtained by absorbing heat (or energy) from a hot reservior, converting some of that heat to usable work, then discharging some remainder of heat into a cold reservior. The Carnot Cycle describes the maximum amount of work that can be extracted when operating a heat engine between to temperature reserviors. This animation shows this process in the physical and graphical sense. It also calculates the efficiency when operated between to temperature reserviors. This template can be used to assist students when given the conditions in the exercise part of the animation. And if the instructor wants to change the parameters, another more generic template can be used and modified.

4. Moving Charge in a Magnetic Field (2.6 Mb, AVI format, compressed - 0.9 Mb)

This animation has three main parts: (1) determining the radius of curvature for a charged particle moving through a magnetic field, (2) knowing the direction the force is applied, and (3) calculating the velocity of the particle based upon a time-of-flight measurement. Four example trajectories are given in the animation. The exercise asks the students to determine which detector will fire given a neutron, deuterium nucleus, and another electron trajectory. It can be pointed out by the instructor or deduced by the student that a neutron will produce no signal in any of the charged particle detectors. In theory, plastic scintillation detectors with photomultiplier tubes can detect neutrons if the neutrons have a direct collision with particles in the detectors thus creating charged particle collision fragments.

The instructor can provide as much or as little of information he or she chooses (as long as the problem can still be solved). The base template leaves blank most of the information for setting up a problem. So new problems can be readily generated. Some curvatures might not hit one of the numbered detectors. In these cases, it is recommended to have the students place an X at the location where the particle leaves the region of uniform magnetic field. This exercise also requires the student to be able to scale distances.

5. Doppler Effect (2.7 Mb, AVI format, compressed - 0.8 Mb)

When a source of sound is approaching or retreating from an observer (or listener) it's frequency, as heard by the observer, is shifted to a higher or lower value. This effect also occurs for light waves enabling radial velocities of distant stars to be determined. Other topics that can be discussed with the Doppler Effect are radar guns, bat echo-location, weather radar, etc. To really appreciate the Doppler Effect concept, one should also mention the role sound intensity plays with the human perception of frequency. This animation illustrates the behavior of the frequency and sound intensity "heard" by an observer near railroad tracks with a train traveling by. The sound waves being shown in the animation are not drawn to scale and are only an illustration. The graphs are mathematically correct given an arbitrary intensity, I_o, and source frequency. The base template can be used by modifying the relative velocity, source frequency, sound intensity, and position of the observer to generate further questions or applications of this effect. Observed frequency and intensity can be calculated for any given train position. For further information please refer to the journal article "Overcoming Naïve Mental Models in Explaining the Doppler Shift: An Illusion Creates Confusion", American Journal of Physics, v65, July '97 (618-621). A sound track is on this animation. This sound has the correct frequency indicated in the frames. The sound intensity was varied qualitatively to be consistent with the intensity graph. Individual computer system capabilities may add distortions to the synchronized sound.

6. Multiple Slit Diffraction (1.3 Mb, AVI format, compressed - 0.5 Mb)

The pattern that light creates on a screen due to diffraction through some aperture can be difficult to comprehend. This animation should be presented only after students have been introduced to constructive and destructive interference of waves along with Huygen's Principle. The pattern that ultimately develops on a screen from light having passed through N number of openings or slits, is a superposition of N number of single slit diffraction patterns. The width of each slit, spacing between each slit, and the number of slits is important.

The curve representing light and dark fringes is mathematically correct and has followed equation 18.13 in the text "Vibrations and Waves in Physics" by Iain G. Main, 2^nd edition. The animation starts with single slit interference patterns and progresses into multiple slits. In the limit that N gets very large we have a diffraction grating. The equation dsin(q)=ml describes the appearance of constructive interference peaks for a diffraction grating. One can use the following template (or with less information) to see if students can effectively apply this equation. This is in addition to the exercise given in the animation.

7. Phases of the Moon (2.5 Mb, AVI format, compressed - 0.8 Mb)

It is a common misconception for students to think that the "shadowed" part of the moon is created by the Earth's shadow. This is only true during Lunar eclipses. This animation tries to eliminate this misconception and provide some understanding of when the Moon is visible from Earth. One good use of this animation is to show students the animation then present overhead transparencies of each phase of the Moon. These transparencies are not labeled with respect to whether the Moon is visible or what phase it is in based upon the position of the flag on Earth. The students can be asked to provide this missing information. Here are some graphics for the Moon phases full, waning gibbous, waning quarter, waning crescent, new, waxing crescent, waxing quarter, waxing gibbous. The instructor can arbitrarily stick the "flag" where they want. The orientation (or rotation) of the Moon as seen from the Earth may not be truly accurate. It is important to note the angle made between the Sun-Earth-Moon in conjunction with the phase of the Moon.

8. Earthquake Waves (2.2 Mb, AVI format, compressed - 1.0 Mb)

The earthquake animation illustrates how P and S wave fronts propagate away from an epicenter. The first earthquake wave presentation shows the wave fronts as expanding concentric circles and what effect they have on the seismographs. Illustrating this expanding wave front provides the students a concrete visual illustration on which a more abstract analysis can be built. An abstract analysis is required to determine the epicenter from just the seismograph readouts as given in the second earthquake wave readout.

A template that includes a US topographical map with seismograph readouts can be given to the students as a "hands-on" activity using a compass and ruler. Here is a more generic template in case the instructor wishes to build their own seismograph readout. From the time interval between the arrival of P and S waves, they can determine the distance from each seismograph station. Three stations are required to locate the epicenter. The given seismograph readout can be used or another of the instructors choosing can be generated and implemented.

9. Faraday's Law of Electromagnetic Induction (1.4 Mb, AVI format, compressed - 0.6 Mb)

This animation illustrates three basic ways that an emf (or voltage) can be generated in a conducting coil by virtue of its interaction with an external magnetic field. Both the physical system and graphical results are shown. In the first case, a changing magnetic field strength produces an emf. This first case is a nice condition to apply Lenz's Law. One can determine that the induced current flows in the clockwise direction because the rate of change of magnetic field strength is out of the page. The next case changes the area of the coils. The right hand rule can be effectively applied to determine the direction of the current. The last case involves the coils spinning in the magnetic field. One could apply Lenz's law in each of the cases to determine the direction of the induced emf (or current). In working the exercise, it is important to emphasize that maximum emf occurs when the magnetic flux (or number of field lines) through the coils is changing most rapidly. Here is a still image onto which students can sketch or predict the shape of the graphs.

10. Kepler's Laws of Planetary Motion (2.3 Mb, AVI format, compressed - 0.8 Mb)

Each of Kepler's Laws are presented along with an illustration of their physical representation. Eventhough Haley's Comet is not a planet it does follow Kepler's Laws. It was chosen as part of the animation because of its large size and eccentricity. The concept of equal areas in equal amounts of time can be made more concrete by shading the area in question. In order to get a discernably sizable area when the Comet is at Aphelion (farthest distance), the animation compares it to the number of revolutions the Earth sweeps out in the same amount of time. The exercise requires algebra in applying Kepler's third law to compare the ratios of (T²/R³) for Earth and Mars. The units can be arbitrary (Earth years and Astronomical Units are convenient).

11. Laser (1.3 Mb, AVI format, compressed - 0.5 Mb)

The Helium-Neon laser is used often in physics courses. So it seems appropriate to examine how the lasing process works for this particular type of laser. The He-Ne laser works by an interaction between these atoms and their respective excited states. Thus, students will need to have seen energy level diagrams and be able to relate energy transitions to photon wavelengths.

A brief summary of the general process involves:

(1) Helium atom is "pumped" into an excited state by an electrical pulse. This excited state is meta-stable and takes a long time to decay.

(2) A Helium atom collides with a Neon atom to transfer the Neon atom into an excited state.

(3) The Neon atom decays with more structure in the energy levels. The Neon atom first decays into a meta-stable state which either spontaneously decays or is induced into emission of a photon by another photon of the same wavelength. This is the lasing transition. The Neon atom then returns to the ground state.

The exercise has the student calculate the wavelength of the laser light using the given equations and the energy diagrams.

12. Multiple Lenses (2.0 Mb, AVI format, compressed - 0.8 Mb)

The ray colors presented in this animation are not to indicate that red, blue, and green light wavelengths behave significantly different. Yes, the index of refraction is technically a function of the wavelength of light, but be careful the students do not incorrectly interpret the meaning of the colors in this animation. The different colors signify the three main rays used in geometrical optics for ray tracing. The first part of the animation illustrates how divergent and convergent lenses "bend" or refract light. It also shows how the rays diverge or converge as the object is brought closer to both types of lenses. The last part illustrates a multiple lens system. Both the first multiple lens example and the second can be used as an exercise in ray tracing for the students. The presentation of this animation should include a discussion of virtual/real images and the lens/mirror equation.

13. Planck Curve (1.6 Mb, AVI format, compressed - 0.7 Mb)

All solid objects emit electromagnetic radiation (and absorb it). The Planck Curve (or Black Body Radiation Curve) describes the intensity of the radiation as a function of the wavelength. This animation can be presented in conjunction with a discussion of Stefan's law which describes the area under the curve or the total radiant energy per time emitted. The exercise has the students using Wien's law to determine the temperature of an object based upon the peak intensity of radiation. The curve is mathematically accurate and follows equation 3.26 in the text "Modern Physics" by Kenneth Krane. It is important that students are aware of the scaling on the vertical axis. The relative size of the curves are drastically different at 1000^oC as compared to 10000^oC.

14. Excavation Safety (4.8 Mb, AVI format, compressed - 1.2 Mb)

This is an animated depiction of how a cave-in progresses. Every soil cave-in is unique but there does exist some general features that most possess. The purpose of this animation is to illustrate the more important features and present some basic facts. Excavation safety issues revolve around psychology (or the "Cowboy Effect"), economics, and soil behavior. The psychology part can be very complicated. Supervisor/worker relations (which may include job security), interpersonal interactions, and a false sense that soil isn't dangerous or feeling that only "wimps" get hurt with soil. Economics is always an issue in our free-enterprise system. The temptation to cut back on safety procedures to save time and/or money is a serious issue. And, of course, the behavior of soil is important. What conditions cause soil to move? An excavation with vertical walls sometimes produce signs that soil is not in equilibrium and is trying to move into a state of equilibrium. Such a sign may be cracks or crevasses developing in the ground near the edge of the excavation. This is a sure sign that the soil is unstable and is prone to movement. Here is a still image to point out hazards. A discussion of proper sloping or shoring either before or after this animation shown is recommended.

15. Soil Compression (2.8 Mb, AVI format, compressed - 1.0 Mb)

Soil does not behave like a spring (i.e. it does not follow Hooke's Law). Once compressed it rebounds only slightly upon un-loading. This animation is appropriate for discussing Over-consolidated and Normally consolidated soil. The compression index can be calculated from this type of laboratory test. Here is a still image for discussing important aspects.

16. Soil Consolidation (2.4 Mb, AVI format, compressed - 0.9 Mb)

How long it takes soil to settle a certain amount for given conditions is an important topic in soil mechanics. Plotting deformation versus time provides us information about the duration of settlement. This animation can be presented during a discussion about total settlement, drainage, pressure, theory (differential equation), etc. Here is a still image for discussing important aspects.

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(*The following animations pre-date this project, but have been modified and updated with the help of new software.)

17. Stress/Strain (1.2 Mb, AVI format, compressed - 0.7 Mb)

This animation demonstrates how solids deform when subjected to stress. It can be presented during a discussion of Young's Modulus. This still image(L) can be utilized as a transparency for relating theory with the physical conditions.

18. Central Force (0.9 Mb, AVI format, compressed - 0.4 Mb)

This illustration is to show the physical meaning of an energy versus distance graph for objects under the influence of a central force proportional to 1/r².

19. CAT Scan (0.8 Mb, AVI format, compressed - 0.4 Mb)

The complicated subject of Computer Axial Tomography has been simplified to two dimensions with this animation. This two-dimensional analysis makes the concept for tractable and provides an excellent way to evaluate students understanding of the concept. Students can be ask to determine the shape of the object that is hidden during the scan or the instructor can design their own scanned object with detector signals from this template.

20. Relativity (0.9 Mb, AVI format, compressed - 0.4 Mb)

This animation illustrates the fact that simultaneous events in one frame of reference are not simultaneous in another. The instructor should recommend that students pay close attention to when the animation is moving at normal speed and when it moves in "slow motion". Light travels extremely fast! And this is not evident from the animation.

A discussion should follow that tries to answer the question "who has the 'correct' view?" The answer is that they are all correct. Simultaneity is relative to ones reference frame.

21. Quantum Mechanical Non-locality (0.7 Mb, AVI format, compressed - 0.4 Mb)

This animation demonstrate the unusual behavior of "entangled wave functions" in the realm of quantum mechanics. It has profound influence on scientific philosophy and the present scientific "worldview".

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(*The following animations were primarily designed for an introductory Astronomy course.)

22. Sun's Life Cycle (0.9 Mb, AVI format, compressed - 0.5 Mb)

Stars have a life cycle. They are born, have mid-life, and die. The Hertzsprung-Russel diagram is central to understanding the life cycle of stars. This animation shows the physical state of a star (similar in size to our Sun) together with its position on the H-R diagram as it lives out its life.

23. Tidal Forces (1.0 Mb, AVI format, compressed - 0.6 Mb)

This animation exaggerates the size of the Earth's hydrosphere for illustrative purposes. To fully appreciate tidal forces, one should start with simple conditions (i.e. just the Earth) and progressively add influences that effect the Earth's tidal cycles (i.e. Moon's gravitational pull and the Earth's rotation). The instructor could follow this animation up with a discussion of how the Sun influences the tides (spring and neap tides).

24. Journey Into the Sun (1.4 Mb, AVI format, compressed - 0.7 Mb)

What would it be like to take a journey to the center of the Sun? The journey is a bit fanciful and imaginary but the conditions recorded by the instruments are realistic. While inside the Sun, the behavior of the particles at the sub-atomic scale is animated. A common misconception is that nuclear reactions are happening throughout the Sun. In fact, they are only (or most frequently) happening near the center.

25. Heliocentric Worldview (0.8 Mb, AVI format, compressed - 0.5 Mb)

Both heliocentric and geocentric worldviews are capable of reproducing the behavior of planetary retrograde motion. So why was Copernicus an ardent supporter of one but not the other? Such a question can encourage thoughtful analysis about retrograde motion and the meaning of science and scientific models in general.

26. Geocentric Worldview (0.8 Mb, AVI format, compressed - 0.5 Mb)

This model was considered to be the correct explanation of planetary retrograde motion for many centuries. It was also a less contentious philosophy or explanation in the eyes of most religions during this period of history.

The following animations have been constructed since the original project was completed.

27. Geologic Time (1.9 Mb, AVI format)

This animation illustrates the magnitudes of geologic time by comparing it to distances on a football field. The "100 yd" line corresponds to the formation of earth and the "0 yd" line is the present time. A football marks the time as the animation travels through different periods of geologic time. One important fact to emphasize is that early humans didn't appear until about 100,000 years ago. This is about 0.08 inches away from the goal line. Another concept to convey is that divisions of geologic time are based upon major trends in the evolution of life.

 28. Hydrographs (or Stream Dynamics) (1.3 Mb, AVI format)

This animation illustrates how stream discharge (or water flow) is affected by artificial structures. In particular, how a hydrograph is changed when the drainage basin is developed, flood walls are constructed, and a hydroelectric dam is placed into the river.

AVI Slide Show Software

ESPN Sports Figures - a collection of short AVI and QuickTime movies talking about math, physics, and general science.

Compressed (ZIP) AVI movies about physical systems

Mpeg movies from Kansas State: pole vaulter, car collision, Tacoma Narrows Bridge

NCSA Digital Movie Gallery (Mpeg)

Physical Science and Astronomy Animations from U. of Oregon

• This site contains some nice JAVA applets simulating physical concepts

Virtual Laboratory using JAVA Animations on the TipTop Physics web site

JAVA Physics Simulations

Fowler's Physics Applets, Michael Fowler - University of Virginia

Nice List of On-Line Demonstration Rooms

Dr. John Belcher's Animations of Electromagnetic Phenomenon at MIT

For suggestions, comments, or questions please contact Dr. Alan J. Scott at scotta@uwstout.edu.