Two particles of equal mass have velocities $\overrightarrow {v_1}=4 \hat i$ and $\overrightarrow{v_2} =4 \hat j ms^{-1}$. First particle has an acceleration $\overrightarrow{a_1}=(5 \hat i+5 \hat j)ms^{-2}$ while the accleration of the other particle is zero. The center of mass of the two particles moves in a path of :