Eli5 – Does the suction of a vacuum decrease when the tube is longer? And if so, why is that?
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it’s not noticeable in a vacuum cleaner, but it does decrease. longer tube means higher volume and more mass of air to be moved. by Newton’s second law F=ma, with more mass and same force, acceleration (speed) will decrease
The air moving along the tube feels friction with the walls. So that will slow and impede air flow. Think about two vacuums. One has a 6 inch hose and one has a 600 foot hose. The 6 inch hose will hose lose very little of the suction to friction. The 600 foot hose will lose most of it and there will be air movement, but it will be pretty gentle.
Now, if you block the hose, the game changes a bit. The pressure differential the fan is able to produce will propagate to the end of the hose and you’ll get basically the full suction. (Although for the 600 foot hose it is going to take a bit.) But once you allow air to move, it will drop back to the gentle movement you had originally.
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