Physics
posted by Katelyn .
1. A fisherman's scale stretches 3.6 cm when a 2.5kg fish hangs from it.
What will be the frequency of oscillation if the fish is pulled down 2.7 cm more and released so that it oscillates up and down?
2. Two trains emit 518 Hz whistles. One train is stationary. The conductor on the stationary train hears a 3.1 Hz beat frequency when the other train approaches.
What is the speed of the moving train?
3.When a player's finger presses a guitar string down onto a fret, the length of the vibrating portion of the string is shortened, thereby increasing the string's fundamental frequency. The string's tension and mass per unit length remain unchanged.
If the unfingered length of the string is l= 65 cm, determine the positions x of the first six frets, if each fret raises the pitch of the fundamental by one musical note in comparison to the neighboring fret. On the equally tempered chromatic scale, the ratio of frequencies of neighboring notes is 2^{1/12

I know that K= 680 N/m

1. Yes, k = Mg/X = 681 N/m
The frquency of oscillation does not depend upon how much farther the scale is pulled down. It is just
f = [1/(2 pi)]*sqrt(k/m)
2. The frequency of the whistle from the oncoming train must be 521.1 Hz
I don't have time to do your third question
We would prefer you post one question at a time. You will probably get answers quicker that way. It is also impportant to show your own work
The doppler shift ratio is
3.1/f = V/(340 m/s)
so V = 340*3.1/518 = 2.0 m/s
There is a more exact doppler shift formula for moving sources, but that is accurate enough. 
Ty. I will keep that in mind next time.
If anyone could help with the last one, I would greatly appreciate it.