Demonstrate the unusual motion of a spool pulled by a string. Will the spool roll toward the pull or away from the pull? Or perhaps it won’t roll at all. It all depends on the angle of the string. What about the spool’s diameter or weight—will they make a difference? Test these variables as you teach about torque and balanced forces that act on a pulled spool. A great activity to perform when discussing free-body diagrams. Includes detailed demonstration instructions. All materials are reusable.
Concepts: Torque, frictional force, free-body diagrams, discrepant events. Time Required: 15 minutes Materials Provided: Two spools of different diameters, bolts to add weight, string.