Question

we have a lithium atom (atomic mass m = 6 amu) connected to two very much more massive atoms, as illustrated in the drawing below. We can pretend that the massive atoms don¡¯t move. The spring constants k1 and k2 are 73 N/m and 27 N/m, respectively. What is the angular frequency of the oscillation of the lithium atom? Units: THz (TeraHertz). 1 amu = 1.66 x 10-27 kg.