[quote]Steel Nation wrote:
[quote]WhiteSturgeon wrote:
[quote]spar4tee wrote:
[quote]csulli wrote:
[quote]spar4tee wrote:
[quote]Steel Nation wrote:
[quote]spar4tee wrote:
[quote]WhiteSturgeon wrote:
If you run in the rain, you will get about 50% wetter than if you stood still.
I learned that on Myth Busters. [/quote]
Right. More contact surface area although I feel the difference is negligible.[/quote]
Explain yourselves. Theoretically this is impossible.[/quote]
I don’t know if it’s actually true or not. I didn’t see that episode. If it is true, however, then I’ll know why.[/quote]
It has been years since I saw that one. It has to do with running forwards into raindrops rather than them just falling on top of you. I think there was decided upon some optimal speed at which to flee the rain, but I don’t remember what the verdict was. The best option I believe may have been walking or something.[/quote]
Exactly my hypothesis. It’s all about surface area over time.[/quote]
Yes. Let’s say you’re going from point A to point B which are X miles apart. And it’s raining at N cups per minute per square foot. And your head and shoulders are exactly one square foot. The slower you go, the more rain hits the top of your head. The limiting case is if you stand still, you’re going to collect N cups of rain per minute, forever.So the slower you go, the more rain hits you from above.
Now if you speed up, to say one mile per minute (mighty fast walk), you’re going to get N cups on your head, since you’re out for a minute, but you’re also going to get some rain on your front that you did not get while standing still. The amount of rain you get on your front depends on the relative rates of your forward motion and the speed of the raindrops coming down. For instance if it takes a second for the raindrops to fall from your head-height to the ground, (lets assume: 5 feet) and you move forward ONE foot during that second, you’re going to intersect about 1/5 of the raindrops ahead of you that second.
The limiting case here is if you went at infinite speed, you would not get any rain on your head, but you would have encountered every raindrop falling in your cross-section in the path from A to B.
[/quote]
You are going to get hit with every rain drop falling in your path from A to B regardless of velocity. For this to NOT happen, you would have to be physically absent from your own path, which is impossible, teleportation fantasies aside. The amount of rain you’re hit with in the frontal plane is a function of the flow rate of the rain, and the distance traveled. It has nothing to do with velocity.
Think about it: if time froze, and every rain drop between points A and B hung in the air, it wouldn’t make any difference if you ran through them or walked through them; they would hit you just the same.
However, the amount of rain that hits you in the transverse plane (plane parallel to the ground) is a function of the flow rate of the rain, and time. So the amount of rain that hits a given body in the transverse plane is proportional to surface area and inversely proportional to velocity.
Since the amount of rain that hits you in the frontal plane is constant, and the amount of rain that hits you in the transverse plane is inversely proportional to your velocity, you will get less wet the faster you move from point A to B.[/quote]
I think the hypothetical situation is operative of a model in which velocities differ but the time is the same, which screws with the rhetoric a bit. We should also assume the flow rate isn’t continuous which would require some integration to balance the models.
