A ceramic coffee mug, with or without liquid inside, is tapped by a metallic object (stainless-steel spoon). Such tapping generates a resonant sound which alternates between low-pitch single tone and high-pitch dual tone at every pi/4 radian (45 degrees) due to the presence of a massive handle of the ceramic coffee mug.
Potential Discovery or Invention
A metallic mixing bowl is filled with dihydrogen monoxide (H2O) liquid. Tapping the metallic mixing bowl by a metallic object (stainless-steel spoon) generates a resonant sound. Varying the angle of the metallic bowl by pulling a fishing line attached to the edge of the mixing bowl continuously varies the tone between low pitch and high pitch.
