When Is Lifting an Advantage? In response to Wayne's 10/6 post.


A couple of questions:
1    Shouldn't the float time and the distance of the float be related to the speed over the ground?

I would think that if the body is moving at 11.11 feet per second, and is off the ground for 0.02 of a second, then the distance travelled in the float should be 11.11 x 12 x 0.02 = 2.67 inches. If he floated for a greater or lesser distance, he would be off the ground for a greater or lesser time. I don't think you can ascribe arbitrary 2 inches or 4 inches for this calculation. While in theory there would be a slight slowing while in the air, for the very short time involved, I think this can be ignored - at least for this level of analysis.

Your alternative assumption with the walker floating 4 inches in 0.02 second, would give him a speed over the ground of 16.67 feet per second while he was in the air. This is a 50% increase in speed compared with his average speed. I don't think anything like that would happen. If it did, a massive amount of energy would be involved.

2    At the start of the Energy analysis you state:
"If there is little or no extra effort (energy) to
achieve the float, then there is little to no energy penalty for the loss of
contact." 
Surely, to achieve a float, it is necessary to lift the whole body mass into the air, and this must require some energy. I don't think you can ignore this. I would expect that this is the major aspect which should be taken into account.

Regards,

Jack Tregurtha

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