Apple QuickTime movie | 1995-07-15 | 6.3 MB | 512x276 | 30fps | 1 minute, 12 seconds
Transcription: One force that we encounter every day is friction. If you push a book across the table, you find that friction resists whatever direction you push. If you start pushing gently, you'll find that the friction force is variable. It resists to a point and then breaks free. Can you feel that friction decreases slightly as the book starts to move? We say that the static friction, when the surfaces are stationary, varies up to a maximum value. The kinetic friction, when they are moving, is less than the maximum static friction. That's why a skidding car takes longer to stop than one whose wheels are ...
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