Pulley'ing Your Own Weight

A spring scale.CopyrightCopyright Malinda Schaefer Zarske, ITL Program, College of Engineering, University of Colorado at Boulder, 2005.

Each group needs:

• 2 small pulleys (purchase from a hardware store, or use a thread spool with a chopstick, straw, pencil, dowel, toothpick or wooden cooking skewers that fits through the spool hole as an axle, allowing the spool to rotate freely around it)
• 1 meter of string (strong enough to support the object being raised)
• A weight to be raised by the pulley (for example, a bar of soap or a plastic milk/juice jug with water or sand inside; the object should weigh ¾ of the maximum weight that can be measured by the spring scale)
• Pulley'ing Your Own Weight Worksheet (PDF)

For the entire class to share:

• Masking tape
• Spring scale (one per team if available, or a few to share with the class; available from science supply catalogs, stores or websites)
• String (if using spools for pulleys, cut extra pieces, as needed, to tie axle to weight)