Why do doors close easier when a window is open?

Question

If you close your bedroom door and then close it again with the windows in the room open you may notice a big difference on how easily it swings shut

In: 9

Answer 1

Air pressure. Closing the door creates a small air pressure gradient. That has to go somewhere. It can go under and around the door, as well as other small orifices in the room or an open window. It is much easier for it to go through an open window, so it offers less resistance as the door is closing.