acoustics Physics questions

An air column is open at both ends. The air in the column is caused to resonate by a tuning fork with a frequency of 680 Hz. The air column is 0.75 m in length. Which of the following diagrams best represents the resonating air column? 1) 'v 7" LA ii) :1: iii Three tuning forks are struck at the same time. Their frequencies are 250 Hz , 245 Hz and f3 Hz. The beat frequencies of 2.0 Hz, 5.0 Hz and 7.0 Hz are heard. What is a possible frequency (fg)of the third tuning fork? O 247 Hz O 257 Hz O 238 Hz O 243 HzA trumpet acts like an air column that is Open at both ends. A trumpet player uses valves to add different lengths to the air column. When the trumpet is played with no valves, it plays its first harmonic note with a frequency of 115 Hz. When the player presses the first valve she adds 0.179 m to the length of the air column. What frequency note will the first harmonic have when the first valve is pressed? 0 103 Hz Q 108 Hz 0 57.5 Hz 0 cannot be determined without more information