You will need:
- Simple protractor (without any holes in the centre or extending lines)
- Smooth table surface
Have fun with a simple protractor and learn all about ground effect.
INSTRUCTIONS
- Clear a smooth surface where you can try this experiment. Make sure there isn’t any dust or dirt on the surface.
- Holding the protractor between your thumb and index finger, place it a millimetre above the surface with the straight side facing forward.
- Also, make sure that the flat side of the protractor faces upwards while the curved edged side is at the bottom.
- Take a few practice shots, but try and release the protractor a millimetre over the surface pushing it forwards, so that it may glide towards the other end.
RESULT
With a few practice attempts you should be able to glide the protractor effortlessly over the surface till it reaches the other end. This is a result of ground effect. The bent edges on one of the surfaces of the protractor are responsible for this. These bevelled edges catch air as the protractor begins to move. As soon as the air is caught beneath, it creates a cushion not more than a millimetre high between the protractor and the table which helps the protractor to glide effortlessly over the surface. Ground effect has been used during take-off of aircraft, and also for creating Ekranoplans (machines which would hold a large number of people, but fly 2-5 metres above the ground using only 1/8th of the power used by planes) during the Cold War.
