Tales from the Prep Room: Making Sand Swim

Produced by the Royal Institution, this short video shows how compressed air can have some unusual effects on the properties of sand.

Passing compressed air through a layer of sand causes the sand particles to flow over each other similar to a fluid. In the 'fluidised bed' the sand acts like a liquid and objects on the bed will either float or sink depending on their density. This is clearly demonstrated in the video clip.

Fluidised beds are used in chemical and process engineering in applications such as reactor vessels, combustion chambers and in the food industry to quick freeze small items.

• URL: http://stem.org.uk/rx867