Pump it Up

A timber, black and orange exhibit table with two information panels at the rear in the same colour scheme. On the table top sits two piston devices with blue bases and a series of weights at one end. Thre is a red joystick and pressure guage at the other end.
A timber, black and orange exhibit table with two information panels at the rear in the same colour scheme. On the table top sits two piston devices with blue bases and a series of weights at one end. Thre is a red joystick and pressure guage at the other end.

Pressure applied over an area generates a force that can do work. Changing the area or the pressure increases or decreases the force.

How it works

One narrow and one wide piston are pumped up to lift masses to a certain height.

Things to try or ask around the exhibit

  • Do these pistons lift the mass the same way?
  • Which piston lifted its mass the highest?
  • Which piston showed a higher pressure on its gauge?

Background

Pneumatic lifts use air under pressure to raise pistons and lift heavy things. In this exhibit, the wide and narrow pistons are both carrying the same mass, but they lift their masses to different heights and under different pressures.

The wide piston uses a much lower pressure, but only lifts its mass a short distance. The narrow piston lifts its mass higher but it uses a much higher pressure to do so. This is Pascal's Principle (named after French mathematician Blaise Pascal), which relates to force being applied over a surface area to generate different amounts of pressure (often measured in pascals or kilopascals).

Finding the science in your world

Pneumatic (air-based) and hydraulic (oil or water-based) pistons are used in many ways. When a mechanic lifts a car on a hoist, they are putting oil and air under pressure in a hydraulic lift. When you drive a car, it uses hydraulics and pneumatics to work the brakes and steering. The next time you see a garbage truck lifting a wheelie bin, or a giant excavator moving piles of dirt, see if you can spot their moving pistons. Pneumatic machines like jackhammer drills often make a ‘hissing’ sound, because air leaks out under pressure.