# Running aid

1. Jun 17, 2007

### robhlee

Hello I am quite a physics noob and the following is something I wouldn't bet on but is more of physcis concept practice. But if it works, great!

Specific questions/problems that I would like an answer to will be denoted by a number and the blue twirling smiley(:rofl:), for your convenience. And grey font is stuff unnecessary for you to get the basic idea.

I am a daily runner and often times imagine running being more engaging/fun. I was wondering if there was a way to substantially increase stride length and/or height achieved while running (Moon Shoes -- pffft! what a rip off:grumpy:), without substantially increasing the level of fatigue induced. So, i came up with a hydraulic-eddy current device. (I uploaded a pic, should be somewheres)

Basically, the force of your body weight and running when your foot comes down powers one end of a hydraulic pump, the other end volleying a strong NdFeB magnet into a copper section of a pipe (btw -- i do have a basic understanding oif the relationship btwn hydraulic machine's surface areas and force translation). The pipe is strapped onto your back. The eddy current reaction will stop the magnet, resulting in a force on the pipe, and thus you, upward. (If you contest to the short time a force will be induced, if the idea works, i intend to stretch the time the force is present by putting gaps in the copper at the bottom of the section progessively making it into a solid pipe at the top of the section, balancing the velocity of the magnet and the total resistance of the pipe so that a constant force is present for a longer duration.)

If the volleying action (will the magnet's release cause a force back onto the hydraulic machine and counteract any effect of eddy currents?1:rofl:) is not workable then an alternative is to keep the magnet on the surface of the piston, so no volleying is done, and the piston just runs through the length of the copper section.

I know there are other technicalities like how will the piston re-set for the next step (and i do have ideas), but i just want to see if the basic idea works.

Are there any counteracting/balancing forces that will inhibit a net force (albeit periodic)? 2:rofl:

Will the hydraulic fluid flow fast enough to accelerate the magnet?3:rofl:

Last edited: Jun 17, 2007
2. Jun 19, 2007

### robhlee

plz someone give input and arguments...

3. Jun 19, 2007

### ice109

Last edited by a moderator: Apr 22, 2017
4. Jun 19, 2007

### Danger

I haven't commented because I don't know anything about eddy currents. What I do wonder is if there would be any inherent advantage to that over using air compression or springs in that same piston area.

5. Jun 20, 2007

### minger

Hi, I'm a runner as well, although not very proficient. Anyways, without going into the "will it work" if you are getting "launched" in the air either higher or farther, it reasons to me that more force is being exerted on your legs.

Think of just standing on a platform that will spring up. You will need to exert force to keep your legs straight.

So, you may go farther and faster, but I think that it will increase fatigue.

6. Jun 21, 2007

### robhlee

well, as for the advantage over air, i am not quite sure but wouldn't alot of energy be wasted in compression (heat involved, etc.)?
And for the spring, (equation being f=-kx) the distance compressed is the problem when trying to attain high force. that's why pogo sticks are the way they are, allowing for greater compression distances. That poweriser thing is pretty cool, but its expensive, probably dangerous (the contact surface area is small, like a pogo stick's-- btw does the smallness of the surface area contribute to the force exerted back upward onto you?), and probably has a pretty flat learning curve.

Hey minger, (in response to your platform-spring example) the thing about this device though is that the hydraulics directs the force (given by your weight) to the pipe, which is attached to your back.

7. Jun 21, 2007

### Danger

You might be right. Since I don't know about eddy currents, I have no way to compare the efficiencies.