10+
Gallery 8

Suck and Push

A large timber and glass table, with two tubes going into the air, and the words suck and push along side either tube.
A large timber and glass table, with two tubes going into the air, and the words suck and push along side either tube.

It is easier and more energy efficient to pump water from below (normal pump) than to try and draw it up from above (using a vacuum pump).

How it works

Try to either pump (push up) or ‘suck’ (pull up) water in two very tall pipes. Compare whether one pumping method requires more energy or is more successful in moving water furthest up the pipe.

Things to try or ask around the exhibit

  • Which type of pump seems to be more effective in moving water upwards?
  • Where would you use a vacuum pump compared to a pressure pump?

Background

Water reaches the top of the tube when it is pumped or pushed up, but only rises part-way when it is pulled or ‘sucked’ up.

Suction is an everyday term for the force that is created when you lower the pressure in one part of a system to create a difference in air pressure.

Water will rise up a tube when the pressure pushing the water up is greater than the pressure pushing it down. If there was a vacuum above the water in the tube (i.e. no air pressure pushing down), normal air pressure at the base of the tube would push the water up to a height of about 10 metres.

Finding the science in your world

'Suction' pumps are less efficient in pumping water from one place to another, although they do need to be used in certain situations such as swimming pools.

Water pumps are often attached to water tanks, because water from the tank needs to be released under pressure to allow the water to flow to different areas around a property.