"a normal sized cube of 1 kg lead falls slower than a compressed smaller volume of 1 kg feathers."

You guys have had enough time to think about this one and Sam provide the right backdrop of the the example. While I'll admit their is a type in the example the basic underlying thought is not correct.

The example tries to show that :

-1- You can't reach a truthfull conclusions without specifying a multitude of conditions. (vacuum or air, both volumes of the same shape

-2- That something that is the case in in particular set of conditions may not at all be true in another set of conditions.


Typically if BOTH the lead and compressed feathers come in the shape of a cube and are examined in air than the lead will drop with a creater velocity.

If the same is done in vacuum then both will drop equally fast

Now when the feathers are compresses in to a volume that resembles an aerodynamic efficient arrow shape than it will drop at a greater speed than the lead with a cubuc shape.

It is the same with boat design. A certain setup may seem inefficient but when another aspect (compressibility) is taken into account it may proof more suited to what you want to achieve. This is thinking "multi-dimensionally"

With regard to same, he is right that you will have a very hard time compressing feathers to a density greater than lead. The placing of the word "smaller" is misleading indeed. I should have written "... compressed, smaller crossection, volume ...."

But even that is not complete as then I pretty much also need to define WHICH crossection I'm talking about and so on. I tried to keep the phrase simple and thus ended up making a misleading phrase.

Best would have been to choose something else than lead.

Best would probably have been.

"... a normal sized rectangular carton of milk. weighing 1 kg, falls slower than a compressed smaller volume of 1 kg feathers ...."

Wouter