Why does the door shut harder when the window is open?

Question

You know how when the window is open, and you're not used to it being that way, you'll barely shut the door and it will slam? Why is that?

Answer 1

Because shutting the door creates a low pressure zone behind the door, and the air pressure difference between each side of the door creates a net force on the door which acts counter to the closing motion, making the door harder to close. However, when a window is open in the room the low pressure zone created by the closing door can be rapidly filled back in with air influx through the window so that the pressure difference doesn't arise.

Answer 2

when you shut the door the door is pushing air in the house.

when the windows are shut, the it takes longer for the door to shut cuz all that air has to go somewhere (it blows out the door as you shut it).

when the windows are open, the air easily escapes through the windows and so the door doesn't meet with as much resistance.

Answer 3

It's because of the air coming in the window.