Thought experiment: Running

Would null-momentum much difference for long distance running?

It might make a difference for sprinting (e.g. 100 metres) where acceleration is critical, but what about a marathon, where acceleration per se is not such an issue, more sustained speed. Less energy would be lost to bounce each step, hence more (personal) energy available to sustain a speed, so perhaps faster overall?

How big an effect would that be, significant or small?.

But could you run anyway?

Running means your feet are out of contact with the ground for part of the stride. If both your feet left the ground you would stop forward motion immediately (air resistance). But gravity still works, so at least one foot will always be touching the ground anyway, since if both were feet off the ground, you would instantly be at terminal velocity back toward it, stopping when you re-touched.

Hence, you could not actually run (or jump) at all. The action would be something like a weird-looking super-quick walk: your swing leg would be instantly ready to re-contact every stride. It would take some getting used to the new action and leg control, but surely no more than any recovery from injury or at worst the equivalent of a child learning to walk.

It would definitely look very weird, but would it be quicker than running or slower? How important for speed is that leap from foot to foot of running vs. the advantage of no momentum?

Would null momentum be better for long or short distances or worse for either or both?

Ground rules:

Suppose, as in “MOMENTUM”, that a miracle occurs (AMO) and out of thin blue air you now have a small device that removes momentum for the object it’s attached to.

Set aside for the moment (groan!) potential non-conservation of energy. Upcoming blog on that, I will put blog number here when it’s published.

Some (arbitrary) limitations:

  • only the object itself (defined somehow);
  • an “encompassing” effect, so a bucket of water nulled includes the water IN the bucket; a car includes the air inside, the engine parts, etc.;
  • the effect ONLY breaks whatever the link is that requires conservation of momentum, all other physical attributes remain and all other forces, etc. remain (e.g. gravity).

See other blogs (and comments) for other possible limitations and/or physical laws/issues.

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