The Glass Drop With a Hidden Weakness

Transcription

But snap its tiny tail, and the whole thing flies apart.

Meet Prince Rupert's drop: molten glass cooled suddenly in water.

The outside hardens first. The centre cools later and tries to shrink, but the solid shell holds it back.

So the skin is squeezed tight, while the centre is stretched.

The squeezed skin makes surface cracks harder to open.

But break the tail, and a crack can reach the stretched interior.

Stored energy drives branching cracks through the drop.

Strong head. Fragile tail. The same piece of glass.

Attribution

Laboratory footage: Purdue Engineering, ‘Prince Rupert’s Drops: 400 Year Old Mystery Revealed’ (2017), via Wikimedia Commons, CC BY 3.0 (cropped, retimed, original soundtrack removed); original 3D teaching animation, graphics, editing and illustrative sound cues: Ask Pandi; narration: ElevenLabs, George. CC BY 3.0: https://creativecommons.org/licenses/by/3.0/ ^{[1] [2] [3] [4]}