Beast Tamer
S03E14 Spinning Things
Many objects spin, including bicycle wheels, footballs, computer hard disks, and even our planet. These spinning items possess inertia, allowing them to continue their motion unless acted upon by an external force. For instance, bike tires rotate until brakes are applied, and a football spirals through the air until it's caught. Remarkably, the Earth maintains its rotation continuously, day and night, week after week, and has been doing so for more than four billion years.