Falling Whistles
Falling Whistles sells whistles for $34 to $104 to raise money for education, advocacy, and the rehabilitation of war-affected people in Congo. The organization got its name from a journal written by its founder, sharing his experiences during a trip to eastern Congo in 2008. During that trip, Falling Whistles' founder met a group of five former child soldiers who told him that some children who were too young to carry weapons were sent into battle armed only with whistles. By wearing whistles, the campaign aims to use this weapon as a tool of protest and to raise awareness of the situation in Congo. As of September 2010, $500,000 has been raised.
Physics of whistles
A whistle is a device that makes sound from blowing air. The physical theory of the sound making process is an example of the application of the science of fluid dynamics. Knowledge of the geometry, dimensions and fluid properties can allow prediction of the properties of the whistle. The principles relevant to whistle operation also have applications in other areas such as fluid flow measurement.