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Gallery 7

Whoosh

Small children playing with scarfs that are placed into large air tubes mounted on a wall.
A young girl placing a green scarf in a perspex box that is connect to a series of large air tubes mounted on a purple/blue wall. A woman watches on behind her.

Differences in air pressure cause fabric scarves whiz around a network of wind tubes.

How it works

Insert one or more fabric scarves into an inlet box and watch how the scarves fly through a labyrinth of air tubes.

Things to try or ask around the exhibit

  • How many potential pathways can a scarf travel?
  • What happens if many people insert scarves at the same time into separate inlet boxes?
  • What happens if you put one scarf in quickly after the other?
  • How long does it take a scarf to reach the ground, once it has been ejected?
  • Observe the shape of the scarf. How does its velocity change with its shape?

Background

Air travels from areas of high pressure to areas of low pressure. The fast moving air in the Whoosh tubes is under low pressure. This is a rule of Nature: if a fluid like air or water is travelling fast, then it has a lower pressure than when it is moving slowly. The scarf seems to get 'sucked' into the tubes, when in fact the higher pressure air around you is pushing into the stream of low pressure air.

When the scarf is ejected into mid-air at the end of a tube, it floats down gracefully like a parachute, due to the downward force of gravity and because of its large surface area producing drag, not because of its small mass (or light weight in general public terms).

Simultaneously falling objects will always hit the ground at the same time, even if they have very different mass. However, because of the large surface area of the fluttering scarf, its downward velocity is slowed as the large area of air beneath the scarf resists being pushed out of the way.

Finding the science in your world

Domestic vacuum cleaners rely on differences in air pressure to pick up dirt and (if you're not careful) valuable items!