Why people raise their hand when they knock a door?

Question

Because you can knock a door with your hand down as well and it would be more convenient?

In: Physics

Answer 1

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.