“…pre-tensioned string subject to sinsoial load at both ends where p is the density of the string (mass per unit volume). The total force F(x,t) transmitted through any cross section of the string of area A is given by du(3)(4) F(x,t) = AE dx Assume boundary conditions as follows x=0 u=0 x=L/2 AEOu/dz) = P + Qcos2nft = F(L/2,t)Then from Eq. (3-3), it can be readily shown that cosXz(3)(4)(5) F(z,t) = P + Q ---cos2nft cos(XL/2)(3-6) % = 2nf(p/E)i/'It is convenient to introduce the fundamental frequency» fo, for the free longitudinal vibration of the string.…”