In arrangement given in fig. (8), if the block of mass m is displaced, the frequency is given by

Let the extension in spring A is x, then the compression in string B will also be x. The restoring force on mass is a force given by .k, x. This force acts towards left' Again a force k2, x pushes the mass to the left due to compression of spring B. The net restoring force acting on the mass is k1+k2x force constant =k1+k2 Now T=2πmk1+k2  Frequency n=1T=12πk1+k2m