rain walk or runYou just got out of the office, looking to head home to a soothing dinner, only to find that it’s raining cats and dogs outside – and you forgot your umbrella of course. Do you walk or run to your car to stay as dry as possible? It might sound trivial, but this is a question that has gained a considerable amount of attention from physicists, and other scientists alike. Various suggestions have been made, the most recent of which comes from Franco Bocci of University of Brescia‘s Department of Mechanical and Industrial Engineering. Bocci used mathematics to describe the problem, and found that running is usually best during most situations, however concludes that there’s an optimal pace for particular conditions.

If you run in the rain, you get exposed to rain for a smaller interval of time than walking, however you also maximize the body surface that directly comes into contact with the rain droplets. Bocci take on the issue comes with a twist as he used simplified geometrical bodies, when previous attempts assumed people to be thin sheets or upright, rectangular boxes.

From his paper, which you can read here in its entirety, complete with equations and thorough statements, the author derived these conclusions:

  • “For rain falling vertically, the best strategy is to run as quickly as possible. The same is also true for motion into the wind.”
  • “For motion downwind, there may be an optimal speed, which equals the component along the direction of motion of the wind velocity. This happens only if the ratio between the cross-section of the body perpendicular to the motion and the horizontal one is large enough; otherwise, the best choice is again to run at the maximum speed one can reach.”

In short, the answer depends on the shape and orientation of the moving bod, as well as  the wind direction and intensity. You can say that in the majority of cases, when rain is joined by little to no wind, it is better to run if your intentions are of staying as dry as possible.

Bocci’s paper was published in the journal European Journal of Physics.

[Image credit / story source]

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  1. 1

    hello, the article that is published in this month. “the best strategy in rain” journal-ijfps, is the final conclusion of this problem.

  2. 2

    Dude, read the paper properly! The conclusions the ‘author derived’ according to you is actually what was already found BEFORE that paper! The line before your copy-paste said: “Qualitatively speaking, the results found >>up to now<< can be summarized as follow"

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    Hey…( really i dont want to talk more about this stupid matter) ??has been found??? What has beed found?? The area of orthogonal projection of ellipsoide has been found the same way in ( my) article 2. The object could lean forward in another articles? 3. They thought it moves in the given time??? 4. They thought about accelation of the body??5. They mentioned that there is constant range in rectangle model?? So i said” the paper can be the last conclusion of the problem in theory”… The point of my article is that to solve this stupid problem( run or walk) it does not need a high level of math.( plz..dont think the solving used a complicated way is more wothy than a simple one..i made the artle for a baby student like you)
    In fact other articles many mistakes…and i talked with prof.Bocci. he said that ” absolutely correct”

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