Tendons are, essentially, elastic cords stretched between two fixed ends; as such, they can support standing waves. These resonances can be undesirable. The Achilles tendon connects the heel with a muscle in the calf. A woman has a $20-$cmcm$-$long tendon with a cross$-$section area of $120$ mm$2$mm$2.$ The density of tendon tissue is $1100$ kg$/$m$3$kg$/$m$3.$

Part A

For a reasonable tension of $500$ NN $,$ what will be the fundamental resonant frequency of her Achilles tendon?

Express your answer with the appropriate units.