How does a whistle work?

A whistle works by utilizing the Bernoulli principle, which describes the relationship between pressure and velocity in a fluid. Here's a basic explanation of how a whistle functions:

1. Air Pressure: When you blow into a whistle, you increase the air pressure inside the whistle chamber. This high-pressure air is directed towards a sharp edge called the "lip" or the "fipple."

2. Bernoulli Effect: As the pressurized air passes over the lip of the whistle, it experiences a sudden change in velocity. The air speeds up as it flows across the lip, creating a region of low pressure just above it.

3. Vibration: The low-pressure region causes the air to pull back towards the lip. This creates a cycle where the air alternates between high and low pressure, resulting in a rapid vibration of the air molecules.

4. Sound Generation: The rapid vibration of the air molecules creates sound waves. The shape and design of the whistle, particularly its internal cavities, amplify the sound waves and give it a distinct pitch and tone.

5. Feedback Loop: The vibrations inside the whistle create a self-sustaining feedback loop. As the air oscillates, it generates more vibrations, leading to a continuous production of sound until you stop blowing into the whistle.

In summary, a whistle produces sound by harnessing the Bernoulli effect, which allows for rapid vibrations of the air molecules, resulting in the emission of audible sound waves.