Because you can knock a door with your hand down as well and it would be more convenient?
In: Physics
I imagine because it’s easier to control the force and thus the volume of the knocking, especially since the door’s resonance and resistance to knocking is usually an unknown until the first knock, so that if more or less force is called for on subsequent knocks you can make quicker and finer tuned adjustment with your raised hand.
Door knocking movement with my arm down is actually rather uncomfortable and creates a weaker knock. Much easier with arm raised. Do you truly experience the opposite?
This is an awesome question.
Raising your hand first changes the muscles groups, what joints get stressed, if gravity is working for you or against you, how close you have to be to the door, etc.
Having your hand down and flicking your wrist to hit the door with knuckles may sound easier on paper, but it’s more likely to be uncomfortable, painful, requires you stand uncomfortably close to the door, and uses more energy to get a loud knock.
Doors have been made with door knockers built in for centuries. The door knockers are placed at eye level. You’d have to raise your hand to use the door knocker. Door bells eventually replaced door knockers.
Although the knockers are no longer part of the door, the practice of raising your hand to knock remains.
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Am I the only one here that does not understand the question being asked? Is OP suggesting that you can somehow knock on the door with your hands down by your sides? I would like a diagram or video please.
So I can see my hand to get an accurate knock without awkwardly looking down?
As someone raised in The Jehovah Witness Cult, I perfected the underhand knock as it was very weak and therefore the “householder” would not answer the door.
When you extend your arm, you knock with your arm.
When you keep the arm close to your body, you knock using your wrist.
Forearm is weak and not comfortable for most people so we raise the arm to make room and knock with triceps.
It’s more ergonomic. Your hands are still in a fairly neutral position (consider your palms) compared to lowering your arm, where you need to rotate your hand out so your palm faces the door and you can knock on it. When you raise your arm, your upper arm is doing most of the work, when you lower your arm, the smaller muscles in your forearm do the coordinating, again in a rotated position. Gravity also helps you knock on a door when your hand is up, vs when it’s down. You can knock on a door without rotating your hand, but that’s actually more awkward because now the outer muscles of your forearm have to pull your hand up, so to speak. Sometimes people knock like that, but only with a finger or two and usually just to get someones attention, not announce to an entire house that you’ve arrived since it’s not as loud as a “traditional” hand-up knock.
Also, historically, doorknockers are on the upper door near face level.
Source: I’m an industrial designer.
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