Smarter Every Day’s feature on Prince Rupert Drops highlight’s the science of why Prince Rupert Drops work the way they do.
The drops are created by dripping molten glass into cold water.
Per the video, the glass forms into a drop shape as it hits the water, and the surface of it contracts rapidly as it cools. The glass towards the center cools more slowly, and this causes the glass to remain in a state of tension.
This makes the glass in the head of the drop very strong, but the tail extremely sensitive to pressure, and stores the kinetic energy of the contraction. Any disturbance to the tail, and the entire drop shatters in spectacular form:
Granted that glass is pretty easy to shatter anyway – I wonder if there’s potential for storing energy this way?