MSP2 (Middle School Math and Science Portal 2) is a social network for educators. SMARTR is a related math and science site by kids for kids.
I was looking for good physics videos for 8th grade or so, and I found these links in MSP2's blog:
A great collection of science-focused videos from NPR's Science Friday.
The Science of Speed
The Science of Speed, produced for the National Science Foundation (NSF) and written and hosted by Diandra Leslie-Pelecky, explains the scientific principles that are so essential to the NASCAR experience. Viewers learn how science makes cars powerful, agile, fast and safe – and how these same principles affect their own cars.
Science of NFL Football
In America, the autumn season means two things–back to school and back to football. To celebrate both events, NBC News’ educational arm, NBC Learn, teamed up with the National Science Foundation (NSF) and the National Football League (NFL) to release the “Science of NFL Football”–an informative 10-part video series that explores the science behind America’s most beloved sport.
Science of the Olympic Winter Games
NBC Learn, the educational arm of NBC News, teamed up with the National Science Foundation (NSF) to produce Science of the Olympic Winter Games, a 16-part video series that explores the science behind individual Olympic events, including Downhill and Aerial Skiing, Speed Skating and Figure Skating, Curling and Hockey, and Ski Jumping, Bobsledding and Snowboarding. Each video is complemented with lesson plans which include fun classroom activities. The lesson plans were written by teachers at Academic Business Consultants for grades 6-9 and are aligned with California State Standards.
GAMES AND INTERACTIVE SITES
Do you have what it takes to win the Ultimate Race? Find out with the Tryscience Extreme Challenge! Compete on seven courses in four sports- mountain biking, kayaking, rock climbing and snowboarding. You must train and apply the science behind the sport to beat the challenge time and earn each course medal.
Funderstanding Roller Coaster
A Java applet allows students to manipulate their own simple roller coaster. Students can change the height of two hills and a loop, the speed and mass of the car, and the gravity and friction being applied. By experimenting with these variables, students will see how basic physics principles guide the engineering behind the design of real roller coasters.
Amusement Park Physics
You learn how the laws of physics are applied to many favorite amusement park rides, including roller coasters, bumper cars, carousels, and free fall and pendulum rides. A glossary and related resources are provided.
Centripetal Force: Roller Coaster Loops
What can be learned from a roller coaster ride? This video segment of a real ride explains the difference between centrifugal force and centripetal force and illustrates how roller coasters rely on centripetal force to give you a thrilling ride.
At this site, you can design a roller coaster and then climb aboard and see how it rides! Watch the ride from right above the car itself or, if your stomach isn’t up to that, from a fixed position away from the track. Students will get a continuous readout of the coaster speed and acceleration. A fun site!