**Problem 3.** *What is the representation of <sup>ω</sup>eqd*,1?

As there exists *meq*1 that differs from *m* if *α* = 2, the equivalent damping free natural frequency, we denote it by *<sup>ω</sup>eqn*,1, is different from the primary damping free natural frequency *ωn* = *km* . Consequently, the following problem appears.
