Buzz
The Dippy BirdThe Dippy Bird, also known as the Drinking Bird or Dunking Bird, is a well-loved novelty toy in the United States and various other nations.
A Dippy Bird consists of the following components:
- Two hollow glass bulbs of identical size
- A lengthy glass tube linking the two bulbs
- Head covered with a fuzzy, water-absorbing material
- Two plastic legs connected by a pivot joint
- Methylene chloride in the lower bulb. Methylene chloride, an industrial solvent and paint remover, is highly volatile, boiling at just 100 degrees Fahrenheit (40 degrees Celsius). This property is crucial for the Dippy Bird's operation, as it allows the liquid to evaporate and condense easily, driving the bird's motion.
To activate the Dippy Bird, moisten its head. As the water evaporates, liquid ascends into the head, making the bird top-heavy and causing it to tilt forward. When the bird dips, the liquid flows back into the abdomen, making it bottom-heavy and tipping it upright again.
Here’s the mechanism behind the Dippy Bird’s operation:
- Evaporation of water from the fuzzy head cools it down.
- The cooling effect condenses the methylene chloride vapor in the head, lowering its vapor pressure compared to the abdomen.
- Higher vapor pressure in the abdomen pushes the liquid up through the tube into the head.
- The influx of liquid into the head makes the bird top-heavy.
- The bird tilts forward, allowing liquid to flow into the head and exposing the tube’s base.
- Vapor bubbles move through the tube into the head, displacing the liquid.
- The liquid drains back into the abdomen, making the bird bottom-heavy.
- The bird returns to its upright position.
If the bird dips into a water-filled cup, the fuzzy material absorbs water again, restarting the cycle.
The warmth from your hand can cause the liquid inside the Dippy Bird to rise.When you hold a Dippy Bird upright, touching its abdomen, the following sequence occurs:
- The warmth from your hand heats the liquid in the abdomen.
- This heat raises the vapor pressure in the abdomen compared to the head (the opposite of what occurs when the head is wet).
- Due to the pressure difference, the liquid moves into the head (flowing from high to low pressure).
- The bird becomes top-heavy and tilts forward.
Explore these fascinating resources:
- The Dunking Bird
- Exploratorium: The Dipping Bird
- Carnegie Mellon University Department of Physics: Heat Engine: Drinking Bird
