Eight equal drops of water are falling through air with a steady speed of $10 \mathrm {~cm} \mathrm {~s} ^ { - 1 }$. If the drops coalesce, the new velocity is:-\\
(1) $16 \mathrm {~cm} \mathrm {~s} ^ { - 1 }$\\
(2) $40 \mathrm {~cm} \mathrm {~s} ^ { - 1 }$\\
(3) $5 \mathrm {~cm} \mathrm {~s} ^ { - 1 }$\\
(4) $10 \mathrm {~cm} \mathrm {~s} ^ { - 1 }$