suppose the length of the tube used in our experiment is 4 m and a tuning fork of frequency 321 hz is used in air where the speed of sound is 342.4 m/s? (give your answers as integers. for this question, the length of the tube is of the entire plastic cylinder, and not the adjustable length of the air column). how many resonances will be observed? group of answer choices 9 7 8 6