The principle of inertia is a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force. We are ...

Experimenting with a rock tumbler and a handful of coins leads to a surprisingly intense process where constant friction, ...

This rock tumbler experiment takes a simple batch of old coins and puts them through a dramatic cleaning and polishing test to see what really happens inside the machine. Watch how the tumbling ...