Naked Science Forum
General Science => General Science => Topic started by: hamza on 05/06/2007 17:00:10
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Is it better to run home or rather walk in order to get less wet? can anyone provide a logical explanation??
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Assuming that the rain is falling at a constant rate and vertically you will get hit by rain on your head and sholders because it is just falling down, and your front will get hit by rain because you are walking into the rain that was in front of you.
The amount of rain falling onto you is proportional to the time you are in the rain, and the rain that you walk into is just proportional to how far you travel (you will hit all the raindrops in a volume that is
your frontal area x the distance you travel
You will walk into the same amount of rain however fast you walk and the faster you go the less rain hits you on the head. So it would make sense to go as fast as possible.
If the wind is blowing things get more complex, and if it is blowing in the direction you are travelling it may make sense to move at the speed of the wind to minimise the rain hitting your front or back.
If the rain isn't constant you probably want to be running when the rain is least and walking when it is heaviest to some extent to minimise the amount of rain you run into.
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Does not the above explanation totally ignore the effect of the clothing.
Although the amount of rain you receive may be proportional to the time in the rain, but the rate at which the rain hits you will vary according to the speed of the rain (which combines your walking speed and the wind speed), and the higher the rate of rain the greater the likelihood that your clothing will become saturated, or otherwise penetrated.
None of this is relevant if you happen to be a naturist, but for the rest of us, it is probably significant.
The question really is why are you worried about the rain (after all, most people are not so worried about immersing themselves in water, but when they do so, they are usually dressed (or maybe undressed) appropriately).
The problem with getting wet is either because of your clothing getting saturated, or because of the chill of the rain (possibly caused by evaporation). In all these matters, the rate of rainfall is at least as important as the absolute volume of rainwater.
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I saw this 'tested' on a children's TV programme. They used sprinklers on poles to make the rain and had teh kids run or wlak a set route around and between teh poles. They weighed the kids before and after to see how much rain their clothes had adsorbed...
The answer from this 'experiment' was that the kid's who'd run were very much drier. I suspect that time is the key here as after a little while in the rain your clothes just aren't going to get any wetter!
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Imagine that you can run very fast. You will sweep out all the rain in a strange person shaped tunnel like volume of air. Running any faster or a bit slower wouldn't make much difference to how much rain you hit.
Now imagine walking very slowly. The longer you are out in the rain, the more of it hits you, eventually, whatever you are wearing gets soaked.
The overall effect is, unsuprisingly, Spending less time in the rain gets you home drier.
Better yet, get a big umbrella, hold it in front of you and run in the shadow it leaves behind.
Then wait patiently for the ambulance because you won't have been able to see what you were running into (unless you had a transparent umbrella with a "windscreen wiper").
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would you get even less wet if you ran directly behind someone else?
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I'm picturing someone standing out in the pouring rain contemplating how to get home whilst collecting the fewest number of raindrops, and getting rather wet in the process. It's an interesting question, but in a practical sense, it really is just a bit of water (...unless mascara is involved of course). Oh, and we're finally getting a few drops here in Australia...awesome stuff...soak it up!
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well then, speaking from experience, I believe that how wet you get also depends on how far your destination, like from school to my house as an hours walk, you might just get wet no matter what you do. I didn't catch a cold, though.
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Assuming that the rain is falling at a constant rate and vertically you will get hit by rain on your head and sholders because it is just falling down, and your front will get hit by rain because you are walking into the rain that was in front of you...
...You will walk into the same amount of rain however fast you walk and the faster you go the less rain hits you on the head. So it would make sense to go as fast as possible.
So why should less land on your head relative to any other part of your body?
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well then, speaking from experience, I believe that how wet you get also depends on how far your destination, like from school to my house as an hours walk, you might just get wet no matter what you do. I didn't catch a cold, though.
Like science guy says, would it not depend on the distance you have to either run or walk in the rain. After some period of time your clothes must reach a saturation point.
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If you run you get "home" quicker and can change into dry clothes or, at least, get out of the rain and start to dry off.
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Yes, I think it's wrong to say that less rain hits your head; if you run (and hence complete the journey in less time) less rain lands on you full stop.
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Yes, I think it's wrong to say that less rain hits your head; if you run (and hence complete the journey in less time) less rain lands on you full stop.
Not sure that you would be correct about this.
If you are running, you will alter the direction the rain falls on you. It will mean that more rain will fall on your face, but less on your neck because the angle of the rain falling will do more to protect the back of your head and neck from rain.
Whether the increase in rainfall on your face will exactly match the decrease of rainfall on the back of your head would rather depend on the exact angle of the rain, the and how the shape of your face and head would effect the amount of water in collects.
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Another factor that might come into play is the amount of water splashed onto your trousers if you're running instead of walking. If your distance is short but covered in deep puddles, walking may leave you dryer overall. But, I agree with all the above assessments.