9.
(a) Using λ = v/f , where v is the speed of sound in air and f is the frequency, we find
λ =
343 m/s
4.5
× 10
6
Hz
= 7.62
× 10
−5
m .
(b) Now, λ = v/f , where v is the speed of sound in tissue. The frequency is the same for air and tissue.
Thus λ = (1500 m/s)/(4.5
× 10
6
Hz) = 3.33
× 10
−4
m.