How fast would someone have to run to run over water?

Question

I have to do a project in college (Going for Game Software Development) where I need to recreate an old crappy Superman game (Superman 64). I want to impliment the ability to run fast enough to go over water, but I don't know if that speed would be so fast that actually running it would make the game unplayable in a *to-scale* Metroplis.

Answer 1

I think the speed of travel is only part of the issue when it comes to running over water (without sinking); the other issue, if not the overall issue, is how to avoid breaking the surface tension of the water. Once that happens you will continue to sink. So in order to determine the speed at which you have to run, consider how much time your foot could stay on the water before gravity causes your weight to break the surface tension. Insects and spiders can walk on water because their weight is very small AND it is distributed over several points of contact (their legs), whereas for a bipedal creature while walking/running it is only distributed over two or one point.

So if you can determine the maximum amount of time your body's weight can be applied to the water at one point of contact before the surface tension is broken, you can eventually figure out how fast you must alternate weight distribution between legs--in other words how fast you have to move your feet while running. From there you can determine the absolute minimum speed at which to remain on the water. I imagine, however, that your legs would have to move faster than 30 steps/second, although I'm too lazy to do the math myself LOL!

Answer 2

None of the other answers are correct. Running on water relies on two things; surface tension and the mass of the water. Basically, the larger your feet and the faster you go, the more weight you can support.

There have been a few studies on the subject, and the conclusion that ultimately came to was that you'd need to run about 33 meters per second, which is about 3 times faster than the fastest human in the world. In order to run this fast, you'd need to put out about 20x more energy than that same human. Basically, it's not possible for a human at the moment.

If you could significantly increase the surface area of your feet, it might be possible, however. Some sort of flippers coated with a hydrophobic material may be able to do it.

Answer 3

I would approximate the answer by using a familiar physical analog: barefoot waterskiing. I would recast the question as follows: What is the minimum speed a barefoot waterskiier must be pulled in order to successfully ski on the surface of the water? I'm sure this could be measured more precisely but my guess -- for the purpose of this answer -- would be, say, around 35 mph. Now, I don't think this gets us to the answer because, a runner is self-propelled and, therefore, will not use their feet as efficiently as a waterskier to overcome the surface tension of the water. Therefore, my guestimation would be to, say, triple the approximation to the waterskiing analog to compensate for the loss of mechanical efficiency due to running instead of skiing. Therefore, my final answer would be approximately 100 mph!

Answer 4

Improve Your Running Technique Now!

Answer 5

Assuming SM weighed 150 pounds, and 8 square inches of one foot touched the water for each stride, leaning forward, water displacement disperses the running force by 2?, or three...450 pounds/8=55 psi. 450 pounds force per step for vertical suspension (tredding water with the feet). For forward motion against air resistance and angular redirection of force from gravity....liquid viscosity of water compared to solid earth is not a factoral difference of 3....is solid earth 100 pounds per gallon? na..going forward would require more engergy per second as force is moved from the direction gravity to horizontal motion. I guess double the 450 to 900 pounds per foot thrust at a rate of one step every tenth of a second. That should make a gaizer or wake fifty feet up and back.

Answer 6

I did a closely related study. I wanted to find how fast you would have to run before you left the ground. You would have look up the specifics, but I assumed the diameter of the earth was 40,000 kilometers. I then asked how far you would have to travel to have the ground fall 9.81 meters below you. This is how far you would have to run in one second. Delta X is the distance you would have to run and delta y is 9/81 meters. This then become a trig problem of which I got approx 14 kilometers.

Answer 7

Just experiment with what looks good in the game. I would guess 200mph???

Answer 8

About one step.