Do you get less wet if you run in the rain? • Hacker News Board

Re: Do you get less wet if you run in the rain?

#11

Post by ajross » Fri, May 22, 2009, 3:51 PM UTC

mronge wrote: post #3

I've spent a lot of time learning math (have a CS degree, which required lots of math). But sadly, I'm not comfortable enough with differential equations to come up with a solution like the first part. It makes sense once someone else has done it, but I wouldn't have gotten that far. Perhaps I just need more practice. Practice makes perfect with math like everything else?

Your CS degree required "math", but not much calculus or analysis. If your degree was in, say, mechanical engineering instead (or anything in the family of applied physics), you'd be much more comfortable with the differential equations. But then, you'd probably have a harder time with discrete stuff like statistics, and the number theory behind RSA would completely baffle you.

Yes, basically. You just need more practice.

Re: Do you get less wet if you run in the rain?

#12

Post by thorax » Fri, May 22, 2009, 4:13 PM UTC

bradlane wrote: post #8

didn't the mythbusters test this in one of their first couple of seasons? iirc, they did, and came to the same conclusion

They originally said if you ran you got more wet: http://en.wikipedia.org/wiki/MythBusters_%28season_1%29#Who_...

But then they changed their mind after that show: http://en.wikipedia.org/wiki/MythBusters_episodes:_Season_3#...

Re: Do you get less wet if you run in the rain?

#13

Post by run4yourlives » Fri, May 22, 2009, 4:16 PM UTC

I won't argue the conclusion, just introduce an anecdotal observation.

When it is spitting or raining very lightly, sit in a stopped car and watch the rain on the window.

Now, speed that car up to about 80km and see what happens. Disregarding spray from other vehicles, odds are that there will be more rain on the windshield in the same amount of time.

Like I said just an observation.

Re: Do you get less wet if you run in the rain?

#14

Post by run4yourlives » Fri, May 22, 2009, 4:18 PM UTC

vinutheraj wrote: post #2

Conclusion: To get to a specific place you get more wet by walking. To travel for a specific period of time you get more wet by running.

In other words, running in the rain gets you more wet, given that all running is doing is reducing your exposure time.

(Yes, sometimes that exposure time can result in you coming out ahead, but it's not really answering the question)

EDIT: What the hell's with the downmods? What is this, reddit?

Re: Do you get less wet if you run in the rain?

#15

Post by antiismist » Fri, May 22, 2009, 4:26 PM UTC

mronge wrote: post #3

I've spent a lot of time learning math (have a CS degree, which required lots of math). But sadly, I'm not comfortable enough with differential equations to come up with a solution like the first part. It makes sense once someone else has done it, but I wouldn't have gotten that far. Perhaps I just need more practice. Practice makes perfect with math like everything else?

I think there is a simpler way to picture this. Imagine a volume of water suspended in the air - the height and width is the person's cross section, and the length is distance to be travelled. All of that water is going to get onto you regardless of how fast you travel. So speed is not relevant there. But for the water hitting the top of the cube, it gets wet only with respect to time, and not to speed.

Conclusion: if the rain is falling straight down, it always makes sense to run.

Re: Do you get less wet if you run in the rain?

#16

Post by ekanes » Fri, May 22, 2009, 5:06 PM UTC

Nice. A fun/rational way to look at what is at heart an emotional decision. :)

Another angle on this is that running spreads the wetness over more surface area (less on top, more on front). If you're wearing a hat, you might choose to walk, etc.

Re: Do you get less wet if you run in the rain?

#17

Post by amalcon » Fri, May 22, 2009, 5:13 PM UTC

yan wrote: post #7

What contributes to how I feel when I arrive isn't the factor of my wetness, but how long I spent being rained on.

I, like you, try to optimize a different thing than the article: I want the time at which my wetness level is normal to be as soon as possible. As such, it makes sense for me to run to shelter if only because I will get to start drying off sooner.

Oddly enough, all three optimizations lead to the same conclusion: that the best thing to do in any case is to run until you escape the rain.

Re: Do you get less wet if you run in the rain?

#18

Post by RiderOfGiraffes » Fri, May 22, 2009, 5:13 PM UTC

run4yourlives wrote: post #14

vinutheraj wrote: post #2

Conclusion: To get to a specific place you get more wet by walking. To travel for a specific period of time you get more wet by running.

In other words, running in the rain gets you more wet, given that all running is doing is reducing your exposure time. (Yes, sometimes that exposure time can result in you coming out ahead, but it's not really answering the question) EDIT: What the hell's with the downmods? What is this, reddit?

If I've parsed that correctly, you're wrong. The following are true:

For a given amount of time, running in the rain makes you more wet.

For a given distance, running in the rain makes you less wet.

Running reduces your exposure time by more than the increase in rain_per_time.

Perhaps I've simply mis-understood you.

Re: Do you get less wet if you run in the rain?

#19

Post by RiderOfGiraffes » Fri, May 22, 2009, 5:15 PM UTC

run4yourlives wrote: post #13

I won't argue the conclusion, just introduce an anecdotal observation. When it is spitting or raining very lightly, sit in a stopped car and watch the rain on the window. Now, speed that car up to about 80km and see what happens. Disregarding spray from other vehicles, odds are that there will be more rain on the windshield in the same amount of time. Like I said just an observation.

Yes, but for a given distance you get less rain on the windscreen when you drive fast, rather than driving slowly.

Re: Do you get less wet if you run in the rain?

#20

Post by xiaoma » Fri, May 22, 2009, 5:20 PM UTC

vinutheraj wrote: post #2

Conclusion: To get to a specific place you get more wet by walking. To travel for a specific period of time you get more wet by running.

I've been running on and off for the past 16 years. In my experience, I do not get as wet while running in the rain as I would just standing in it.

I think there must be a missing variable, such as excess water whisking off more quickly, greater evaporation due to heat transfer or maybe something else.