// chapter 1 , Example1 15 , pg 26
lam=2*0.4*10^-3 //distance between 2 antinodes is  lam/2 (in m)
n=1.5*10^6 //frequency of crystal(in Hz)
v=n*lam //velocity
printf("velocity of waves in sea water\n")
printf("v=%.1f m/s",v)