How Fast Is Kettle Steam?

Steam from a boiling kettle emerges at about 5 m/s — fast enough to whistle. The whistle is produced by air resonating in a small cavity in the spout as the steam pushes through.

A kettle whistles because steam resonates in a small cavity in the spout — the same physics as blowing across the top of a bottle.

• Same speed as a galloping horse
• Fast enough to whistle