# Free for Educators

Whether you’re a teacher or a motivated student, the materials provided here will be of use in the classroom or at your home desk. Most materials in this collection are related to physics, the physical sciences, or math. Some are great “rainy day” activities, others are mentally challenging puzzles, some are just plain fun. All are are based on sound pedagogical principles. And if you’re a substitute teacher, these are an excellent way to engage the class when you lack a lesson plan.

 Physics Lessons with 1080×810 Animations and Teachers Notes Suitable for grades 8-12 Physical Sciences Binary.zip 1.6 MB Redshift and Blueshift: Video demonstrates the relativistic Doppler effect for a binary star system of two equal-mass G type stars. Redshift and blueshift are exaggerated for clarity. The Teachers Notes explains the physics and math, and includes two practice problems with solutions. Doppler.zip 10.1 MB 3-scene video showing the Doppler Effect for sound waves in air. This video includes an audio track, so you can hear the Doppler Effect in the animation, and also for the real-time footage of a trumpet playing a sustained note on a moving bus. e-1.zip 11.8 MB Linear Orbit Simulation: This 2-scene video depicts a hypothetical orbit with eccentricity e = 1. Note: this never happens. Still, we can learn some interesting physics. It’s what’s called a gedankenexperiment (thought experiment). We place two identical Earths in mutual orbit around their barycenter. We position the Moon at a point equidistant from both Earths. Then we watch what gravity does. We look at the resulting “orbit” from two frames of reference (points of view). First, we observe from a frame that is co-rotating with the two Earths. Second, we observe from a frame that is fixed in space and not rotating. The appearance is strikingly different. Elevator.zip 17.9 MB Riding a Wild Elevator: One 5-scene video showing how an observer’s state of motion affects their sense of apparent weight while riding an elevator. Our intrepid observer stands on a scale inside the moving elevator. Various rides ensue. Plots of velocity vs. time are displayed. Light-Clock.zip 4.1 MB Light Clocks, Time Dilation, & Length Contraction: Three related videos introducing the topic of Special Relativity. Video 1: The Light Clock (RT = 1:54) Video 2: The Light Clock in Motion – Part 1 (RT = 2:12) Video 3: The Light Clock in Motion – Part 2 (RT = 2:09) We begin with Einstein’s concept of the light clock. Its behavior at rest differs from that when in motion. The second video presents the effect known as time dilation, and the third presents length contraction. This lesson is a basic introduction to Special Relativity. Four practice problems for students are included. Lightning.zip 6.8 MB Lightning and Thunder: One 3-scene video explaining how lightning forms and how it generates thunder. As a bonus, the Teachers Notes includes a discussion of lightning protection systems with relevant images. Light-Speed.zip 3.2 MB The Speed of Light: Two videos related to the speed of light. Part 1 shows an early attempt to measure that speed in the lab. Part 2 shows a real-time and to-scale animation of a laser beam bouncing off the Moon and returning to Earth. The Teachers Notes provide all the necessary background physics and math, as well as a brief history of attempts to measure the speed of light. One practice problem is included. Midnight-Sun.zip 10.8 MB Two videos showing how, at extreme latitudes, both the Midnight Sun and the Noon Darkness can occur. Both are caused by the tilt of Earth’s rotation axis with respect to the plane of its orbit around the Sun. Part 2 includes an animation of the rotating Earth explaining both phenomena, and a time-lapse photo of the Midnight Sun over Antarctica. Part 1: The view from Barrow Alaska (RT = 3:51) Part 2: Earth animation and Midnight Sun photo (RT = 1:37) Moon-Orbit.zip 4.1 MB This 2-scene animation shows several aspects of the Earth-Moon orbital system, including: •    Earth-Moon system to scale as seen from 1 million km out in space. •    The Moon keeps the same side facing Earth throughout its monthly orbit. •    Both Earth and Moon simultaneously orbit the barycenter of this 2-body system. •    Lunar gravity creates a tidal bulge on Earth that follows the Moon as it moves. •    One orbit of the Moon (one month) takes 29.5 rotations (days) of Earth. Orbit.zip 15.5 MB The Science of Orbits: Four videos show how an “orbit” is a state of motion in which a body is continuous falling toward the Earth, but never getting any closer to the ground. This unintuitive concept is explained in a series of animations starting from basic kinematics. It begins with Galileo’s apocryphal experiment in Pisa, Italy. Power.zip 20.6 MB How We Make Electricity: Nine videos show how we make electricity from natural sources of energy. Video 1 explains the physics of electromagnetic induction. The following videos show how we harvest specific sources. Video 1: The Generator (RT = 1:20) Video 2: Fossil Fuels (RT = 1:48) Video 3: Nuclear (RT = 1:30) Video 4: Geothermal (RT = 1:34) Video 5: Solar Thermal (RT = 1:32) Video 6: Wind (RT = 0:55) Video 7: Hydro (RT = 1:05) Video 8: Waves (RT = 1:25) Video 9: Photovoltaics (RT = 1:35)