Spool Rolls Toward the Pull

The spool may roll toward your hand or away depending on angle. Ask students to predict what will happen. Pull string at different angles. Key idea: The pull creates torque about the contact point; direction depends on geometry. Ask: Why can pulling right make it roll left—or right? Safety and cleanup: Use large spool on floor/table. https://www.google.com/search?q=%22Spool+Rolls+Toward+the+Pull%22+science+demonstration+experiment