Vapor pressure differential is responsible for the bobbing action of a novelty store drinking bird.
A novelty store "Drinking Bird" repeatedly dips is beak into a beaker of water and then bobs back to an upright position. Visible movement of a liquid in the bird's body accompanies the bobbing; the movement is caused by changing vapor pressure of the liquid due to different temperatures at the bird's head and the bird's body. Using a heat lamp on the head does not cause bobbing, but using a heat lamp on the body does cause bobbing.
- Design and Demonstration
- David Whisnant Wofford College, Spartanburg SC 29303
- Jerrold J. Jacobsen University of Wisconsin - Madison, Madison, WI 53706