Atmospheric Pressure
Properties of Matter

Glass Lift

At home for 5-11 11-14


What you need

  • Two plastic glasses
  • Paper towel
  • Hot water
  • Sink
  • Adult help

Instructions

  1. Fill both glasses about 1/3 full with hot water. Carefully swirl the water around one of the glasses and pour the water away - mind not to splash yourself
  2. Dampen the paper towel and place it over the empty glass. Swirl and empty the second glass and place it upside down on top of the first
  3. Hold the top glass in place for ~20 seconds; then use the top glass to pick up both glasses

Results and Explanation

The hot water heats up the air inside the glasses, which expands and some escapes. With the two glasses held together the escaped air can’t get back in as the air inside cools and shrinks. This means that the air pressure outside the glasses is higher than inside and the glasses are pushed tightly together.

These experiments have not been specifically safety tested for home use but we believe them to be safe if the instructions are followed. Adult supervision or direction is recommended as appropriate. All experiments are carried out at your own risk.

Atmospheric Pressure
is a special case of Pressure
2021 IOP Awards

Teachers of Physics Award

Recognising and celebrating outstanding contributions to the field of physics education.

Learn more