Assume a rigid building(assume the building to be like a pyramid and its empty inside) to be vacuum. If we open a hole(about r=.5m), then, how long will it take for the air to take up of the whole space apprximately? Will, it's just curiosity because I found a little pump in a class room could result in fast moving air in the slit around the door... Thank you.. If the condition is not specific enough, please tell me..