When you twang a ruler on the edge of a table, you create vibrations in the ruler. These vibrations disturb the surrounding air molecules, generating sound waves that travel through the air. The frequency of these vibrations determines the pitch of the sound you hear. Essentially, the ruler's motion converts mechanical energy into sound energy.
A ruler is a straight edge
You could align the edge of the object with the zero on the ruler and then read off the marking on the ruler which aligned with the other end of the object.
Straight Edge
A ruler has markings, a straight edge does not. In "straight edge and compass" constructions, you are not allowed to mark the straight edge. Things that are impossible using only a straight edge and compass are possible if markings are allowed (for example, it's possible to trisect an angle using a marked straight edge).
You look at the markings on its edge.
When the ruler is sticking out further from the edge of the table, it is more easily influenced by external forces such as air currents, causing it to vibrate more. The longer unsupported length of the ruler also allows it to bend more easily, contributing to the increased vibrations.
A ruler is a straight edge
the edge
A ruler is a straight edge
A ruler can be classed as a straight edge.
horizontal ruler
Called a straight edge
A Ruler
Horizontal ruler
You could align the edge of the object with the zero on the ruler and then read off the marking on the ruler which aligned with the other end of the object.
Straight Edge
Along the edge.