Egg and sheet
To show the effectiveness of an airbag by challenging the students to break an egg by throwing it at a sheet.
Apparatus and materials
Old bed sheet or decorating sheet
Health & Safety and Technical notes
People holding the sheet should wear goggles. Take careful aim!
a Get two students to hold up a sheet not quite taut between them. Let it hang down, then curve up the bottom to make it j-shaped. If they hold the top and the bottom the egg will have a soft channel to fall into.
b Either demonstrate or challenge the student to throw the egg as hard as possible at the centre of the sheet. The sheet will give and the egg will not break.
c Finally break the egg into a sink or beaker to prove it is not hard-boiled.
This can be used as a simple demonstration of the effectiveness of air bags or seat belts - the students can clearly see that the sheet 'gives' so increasing the contact time and distance, and reducing the average force needed to stop the egg compared with it hitting a wall.
Also the force on the egg is spread over the entire shell not just one point - this is akin again to hitting an airbag rather than the edge of a dashboard.
This experiment was submitted by Ken Zetie, Head of Physics at St Paul's School in West London. He is on the editorial board of Physics Education and regularly contributes to Physics Review.