10K views · 8.9K reactions | Lifting your hand to knock on a door makes use of gravity and gives your knock more impact. When you raise your hand, you allow it to gain gravitational potential energy due to its height relative to the door. As you bring it down, that potential energy converts to kinetic energy, creating a stronger knock that’s more likely to be heard. #science #scienceshorts #physics ️ credits Julien Brown | vt.physics | Facebook