General Question

gondwanalon's avatar

How does a strong head wind effect runners of various body weights?

Asked by gondwanalon (20183points) 1 month ago

Let’s say that there are two runners who have identical 10k finish PR’s from a recent race.

One runner weighs 230 pounds.
The other runner weighs 150 pounds.

They’re now racing each other in a 10K directly against a 25 mph head wind.
Which runner do you think has an advantage while running against this strong head wind? (Light weight runner or heavy weight runner or neither?)


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8 Answers

kritiper's avatar

It’s not about body weight but area presented to the wind for it to catch and provide resistance.

canidmajor's avatar

It also involves momentum and inertia. The greater mass will build up more momentum.

Zaku's avatar

Runners are more complex systems than simple masses or shapes. However the direct first-level cause answer would be that the heavier runner would be affected relatively less, because mass in more than linearly proportional to surface area, and surface area multiplies force from wind. So the heavier runner is probably slightly larger, so although they experience somewhat more wind force, that wind force is lower in proportion to their mass and therefore their momentum, so the wind will tend to slow them less than the lighter runner.

gondwanalon's avatar

Thank you all for the interesting and reasonable responses.

Why I ask this question:

My buddy and I have the same make and model of outrigger canoes. He weighs well over 200 pounds and I’m 141 pounds. In flat water with no wind we’re very evenly match with boat speed. When paddling into a head wind he slowly pulls away while I go into the red zone trying to keep up.

Zaku's avatar

In that case, not only does your body have a lower momentum-to-wind-force ratio, but your canoe is probably higher in the water, too, meaning it resists being blown less because it has less water drag.

gondwanalon's avatar

@Zaku I’m not quite sure what “a lower momentum-to-wind-force ratio” means. But I understand basically that you are saying that the head wind is going to have a somewhat larger effect on me than my buddy.

I realize that my canoe is riding higher in the water makes it a larger target for wind to hit.

Also my smaller body has a slightly greater surface area to mass ratio than my big buddy’s body.

Zaku's avatar

Yes, that’s what I was saying, just using the math term ratio. A ratio is the relative size between two amounts.

The wind force is nearly the same for the two of you. A little greater for him because he’s bigger than you, and little greater for you because your boat is higher in the water than his.

But those differences in the amount of wind force are fairly small. You are both adult men, and your boat’s only a little higher.

What’s a bigger relative difference is your weights. He weighs significantly more than you. And because the greater weight puts hit boat lower in the water, it also means it digs into the water more, which will have it resist being blown more, because there is more of his boat in contact with water to produce more drag. Pushing things through water takes a lot of force, in proportion to how much surface has to be pushed through water rather than air.

He also has more power than you, because he’s usually (without wind) able to move more weight at the same speed. All else being equal, heavy people have more muscle.

gondwanalon's avatar

@Zaku Very good analysis. I know that my bigger canoe paddling buddy is far stronger than me and he must work very hard to move all that mass through the water. It seems very frustrating to him that I’m able to beat him half the time. His usual comment when I pass him or out sprint him is to repeatedly exclaim, “That F’n red boat!!!”. When he beats me I tell him, “Good paddling!”.

I’m pretty sure that I have the advantage while padding in down wind conditions.

I wonder which canoe paddler is more efficient? Efficient in that able to produce the desired result using the less amount of muscle/body weight.

Thanks a lot!

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