Teaching Physics with the Physics Suite Edward F. Redish Home | Action Research Kit| Sample Problems | Resources | Product Information
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When my teenagers were just beginning to drive a car, I told them the following test to see if they were “impaired” too much to drive. Take a dollar bill and have a friend hold the bill from one of the short sides hanging straight down. Place your thumb and forefinger opposite the bottom of the bill. Have your friend release the paper suddenly and try to catch it with your thumb and forefinger. If you can catch this bill three times in a row, you are not too badly impaired. Assuming the bill was falling freely without air resistance (not a bad assumption for the paper falling sideways), calculate your reaction time. That is, how long does it take for the entire length of the bill to fall between your fingers?

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Page last modified August 31, 2004