The essential condition of placing the two masses, so that the system becomes dynamically equivalent, is (where $${l_1}$$ and $${l_2}$$ = Distance of two masses from the centre of gravity of the body and k_G = Radius of gyration of the body)

A. $${l_1} = {{\text{k}}_{\text{G}}}$$

B. $${l_2} = {{\text{k}}_{\text{G}}}$$

C. $${l_1}{l_2} = {{\text{k}}_{\text{G}}}$$

D. $${l_1}{l_2} = {\text{k}}_{\text{G}}^2$$

Answer: Option D