how the frequency of sound produced will change in an aluminium string of 15 cm length

Answer 1

Sound velocity in aluminium is
v=5240 m/s

L=k•λ/2, where k=1, 2,3, 4,...
λ =2•L/k,
λ =v/f,
2•L/k = v/f,

f=v•k/2•L=
=k•5240/2•0.15
=k•174667 (Hz)