A mass of $$1$$ kg is suspended by means of $$3$$ springs as shown in Figure. The spring constants $$\,{K_1},\,{K_2}\,\,$$ and $$\,{K_3},$$ are respectively $$1$$ $$kN/m,$$ $$3$$ $$kN/m$$ and $$2$$ $$kN/m.$$ The natural frequency of the system is approximately )