About a week ago I described a demo with a long stretched
spring. We had it in class yesterday. The round trip time
of a single pulse was measured 30 times (mean = 1.19 sec)
and the speed was found to be in a reasonable agreement
with the v=sqr(T/mu). The tension T =15 N was actually
measured with a forcemeter. A very good agreement with
that formula was obtained when v was determined from
the frequency needed to establish a standing wave.
It shows that the effect of stiffness on the speed of
transverse waves (for our spring) was not significant
enough to change v by more that about 2 or 3 %. The
spring behaved as if it were a rope (mu=0.086 kg/m).
The outcome would probably be different for a much
stiffer spring.
By the way, how many of you remember that the so-
called "spring constant" k is inversely proportional to
the relaxed spring length, L? Take two springs which
are identical in all respects except for their relaxed
lengths. Suppose L1=2*L2. In that case k1=k2/2.
I forgot this and was puzzled for a while.
Ludwik Kowalski