Free falling spinning rectangle

[kurious]

A rectangular piece of paper spins rapidly about its longitudinal axis as it falls
through the air.It takes longer to reach the ground than other shapes of paper.Why is this given that it spends a lot of time edge on to the flow of air and so encounters less resistance from the air than a surface of constant horizontal orientation?
And could I generate enough electricity from a free falling propeller to do something useful with - even if it's only going to turn on a light so I can read a book as I parachute from a plane at 2 in the morning.

 

[drag]

I don't know what you meant about air resistence and stuff,
but I figure that the spinning part depends on start conditions
of the fall, air streams, and lack of symmetry.

As for generating power from a falling propeller, of course
it could be done. But remember the saying (in reveres though ;) ):
what comes down must first go up.

Live long and prosper.

 

[ravenprp]

This phenomenon can be explained by the concept of air resistance or drag. As the rectangular paper falls, it experiences two types of drag - form drag and skin friction drag. Form drag is caused by the shape of the object, and in this case, the rectangular paper has a larger surface area compared to other shapes of paper. This means that it will experience a greater amount of form drag, slowing down its descent.

Additionally, the paper's rapid spinning motion also creates turbulence, which increases the drag force acting on the paper. This further slows down its descent and causes it to take longer to reach the ground.

As for generating electricity from a free-falling propeller, it is possible but would require a significant amount of energy to overcome the drag force and maintain a constant spinning motion. It is unlikely that this amount of energy could be generated from a small propeller to power something useful, such as a light. However, with larger and more efficient propellers, it may be possible to generate enough electricity for basic tasks during a free fall.