Math Is Fun Forum

sarabjot_anand

Member

Registered: 2009-12-08

Posts: 7

Physics

The wavelength for sound in air is 6.8% of what it is in steel.  Its speed in air is 344 m/s.  A person uses a hammer to strike the end of a steel fence which is 84 m long.  This produces a note with a frequency of 3500 Hz [in the air and in the steel].  How long does it take for the sound to travel the length of the fence.

a) through the air
b) through the steel

juriguen

Member

Registered: 2009-07-05

Posts: 59

Re: Physics

Hi!

Lets see if this works. We have the following relation between the wave speed [c] (m/s), the wavelength [lambda] (m) and the frequency [f] (Hz):

Then, for air you use c = 344 (m/s):

Now, for steel you can calculate:

which gives a speed in steel equal to:

We now have all the information to answer the time it takes to travel s = 84 (m):
(a) For air

(b) For steel

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