High School Trying to understand wind forces on a door

[Bendimac16]

So far, rn since i am making a theory, though im coming in a problem, if por example if im talking about of human force against wind, then who would be stronger, considering which impacts more? Idk it just looks a dumb question just to see how much force i need to do if the wind is strong to win it a close the door compared to normal

 

[Mark44]

Idk it just looks a dumb question just to see how much force i need to do

It's not a very well thought out question. It depends on how fast the wind is blowing. I mild breeze blowing at 2 o4 3 kilometers/hour doesn't exert much force in comparison to wind that is blowing at, say, 120 km/hr.

So far, rn since i am making a theory

This is not the place to post personal theories.

 

[jbriggs444]

how much force i need to do if the wind is strong to win it a close the door compared to normal

So, for instance, you are standing at your front door. The door is open and the wind is blowing into your house through the open door. The door opens inward. You are standing in the house and want to swing the door closed. You slowly push the door closed against the force of the wind. You want to know how much force is required to accomplish this.

Does this match what you have in mind?

The first thing that I would consider is the "stagnation pressure" of the wind (Google it). Bernoulli came up with a formula for that.

The next thing that I would consider is where to push on the door. If the door is hinged on one side, where should one push to get maximum leverage?

 

[russ_watters]

Note that how hard it is to close a door in the scenario above depends on wind speed, direction, and how "tight" or "leaky" the building is. If there's no leakage there's no airflow though the door and no force required.

 

[tech99]

Note that how hard it is to close a door in the scenario above depends on wind speed, direction, and how "tight" or "leaky" the building is. If there's no leakage there's no airflow though the door and no force required.

Wind will exert a force even on a static object, due to the change in momentum of the air particles, so no flow past the door is necessary. I remember from the days when we used Imperial units that the pressure exerted by a 10 mph wind on a flat surface was approx 0.4 pounds per square foot. It changes with the square of the wind speed, so will be approx 40 psf at 100 mph.

 

[jbriggs444]

Wind will exert a force even on a static object, due to the change in momentum of the air particles, so no flow past the door is necessary. I remember from the days when we used Imperial units that the pressure exerted by a 10 mph wind on a flat surface was approx 0.4 pounds per square foot. It changes with the square of the wind speed, so will be approx 40 psf at 100 mph.

What I believe @russ_watters is getting at is that if the rest of the house is tightly sealed then no wind will enter the front door. There would be no place for it to go.

There will be a pressure difference somewhere, certainly. For instance if the front door is open then the inside pressure at the back wall may be 0.4 pounds per square foot higher than the pressure outside in the stagnation zone behind the house. But in this situation, the pressure difference across the front door will be zero.

I would be wary of a line of reasoning which relies directly on the momentum of air particles. When one gets into considering multitudes of interacting particles (like $6.02 \times 10^{23}$ or so) the model as a continuous fluid becomes more relevant and tractable.

 

[russ_watters]

What I believe @russ_watters is getting at is that if the rest of the house is tightly sealed then no wind will enter the front door. There would be no place for it to go.

Yes, that's what I'm saying. And that makes it very difficult to model.