Final answer:
Tempo is determined by the speed of the beat, which is the basic measurable unit in music pacing. While rhythm, accelerando, and ritardando influence how tempo feels, beat is where the speed is anchored.
Step-by-step explanation:
Tempo refers to the speed of the music, gauged by the speed of the beat. This is because the beat is the basic unit of measurement when it comes to the pacing of music.
Other elements such as rhythm, accelerando, and ritardando can affect how the tempo is perceived, but the actual speed is determined by the rate at which beats occur. Rhythm can be thought of as the arrangement of beats within a bar, where certain beats may be emphasized or stressed more than others to create a musical pattern.
For example, in the line from the nursery rhyme 'There was an old woman who lived in a shoe,' the beat is consistent, and the rhythm is created through the stressed and unstressed syllables, creating meter or poetic feet which organize the flow of the verse.
Similarly, rhythm in art and architecture, such as the repeating elements of the Great Mosque of Cordoba, can set a visual tempo in a space.