How do I calculate the frequencies of the following?

[riseofphoenix]

7. A steel wire in a piano has a length of 0.9000 m and a mass of 4.000 10-3 kg. To what tension must this wire be stretched so that the fundamental vibration corresponds to middle C (fC = 261.6 Hz on the chromatic musical scale)?


8. The human ear canal is about 2.6 cm long. If it is regarded as a tube open at one end and closed at the eardrum, what is the fundamental frequency around which we would expect hearing to be most sensitive?

 

[riseofphoenix]

Do I use:

f = TM/L√2L

 

[riseofphoenix]

For the first one I got T = 49888794.74

 

[riseofphoenix]

Oh wait the first one is T = 985 N