Shuttle on A String
	Science Process Skills observing communicating comparing organizing relating inferring
	Materials string, 14 inches long washer or other weight plastic straw, 3 inch piece paper clip, large shuttle cut-out tape ruler scissors
	Doing the Activity Tie the washer to one end of the string. Insert the string through the straw. Tie the paper clip to the other end of the string. Tape the space shuttle cutouts to the paper clip, with shuttle running the long way on the paper clip. Hold the straw upright in your fist. Move your wrist in a circular motion. Whirl the straw in a circle, keeping the paper clip moving parallel to the ground.
	Reflecting What is the shape of the path of the spinning paper clip? What would happen to the paper clip if it separated from the string? What keeps the paper clip moving in a circular path?
	Applying Why does the shuttle remain in a circular orbit? What conditions would cause the shuttle to move off into space?
	What's Happening The force on the space shuttle, exerted by gravity toward the center of the Earth, is called centripetal force. There is no centrifugal force pulling outward.
	More Challenges Spin the straw and string at different speeds. What happens when the speed changes? What does the paper clip represent? What does the washer and string represent? What does the straw represent? What does the path of the paper clip represent?
	Activity Source "Toys in Space," Iowa State University Extension- Science, Engineering and Technology Youth Initiative, 32 Curtiss Hall, Ames, IA 50011. To order: publication #4H-87 Level One; 4H-88 Level Two; video 4H-87A, ISU Extension Distribution Center, 119 Kooser Drive, Ames, IA 50011. (514) 294-5247. pubdist@exnet.iastate.edu

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