Final answer:
The string needs to be tight for better sound transmission. Multiple cans and strings do not create a party line. Blowing across a small-necked bottle produces a resonant frequency.
Step-by-step explanation:
The subject of this question is Arts, and the grade level is Middle School.
The toothpick and string experiment described in the first part of the question is an example of sound transmission through vibrations. When the string is tight, it can transmit sound waves more effectively between the two cans, allowing the person at the other end to hear what is being said. If the string is loose, the sound waves will not travel as well, resulting in poor sound transmission.
In the second part of the question, the experiment with multiple cans and strings does not lead to a party line where everyone can talk to each other. This is because sound waves can only travel along one string to reach the person at the other end, rather than being transmitted through multiple strings simultaneously.
In the last part of the question, the experiment with the small-necked bottle and blowing across its surface demonstrates the concept of resonance. The pitch created when blowing into the bottle corresponds to the resonant frequency of the air remaining in the bottle. By varying the depth of air in the bottle and measuring the corresponding frequencies, one can confirm the relationship described by Equation 17.1.