A planet has double the mass of the earth. Its average density is equal to that of the earth. An object weighing $W$ on earth will weigh on that planet:\\
(1) $2^{\frac{1}{4}}\mathrm{~W}$\\
(2) $2^{\frac{1}{3}}\mathrm{~W}$\\
(3) $2W$\\
(4) $2^{\frac{2}{3}}\mathrm{~W}$