Percent error in sound waves

Question

a tuning fork of 365 Hz is placed over a column of air at resonates a positions 15cm and 40cm. what is the velocity of that sound wave? If the temp that day was 25 degrees celcius, what is the percent error for this lab?

Answer 1

This has to be an open-column experiment. (A closed column would have resonances at column lengths that are odd-integer multiples of 1/4 * the applied wavelength, and 15:40 just can't be made into an odd-integer ratio.) For an open column, resonances occur at column lengths that are integer multiples of 1/2 * the applied wavelength. Since the length ratio is 3:8, the applied wavelength is 15 cm*2/3 = 40 cm*2/8 = 0.1 m. This implies an experimental value of c = 365*0.1 = 36.5 m/s. (Could you have meant 3650 Hz for the tuning fork frequency?) The standard formula gives 346.75 m/s at 25 C, so you can figure the error from that.