A cube of steel has a volume of $1.00 \mathrm{cm}^{3}$ and a mass of $8.00 \mathrm{g}$ when at rest on the Earth. If this cube is now given a speed $u=0.900 c,$ what is its density as measured by a stationary observer? Note that relativistic density is defined as $E_{R} / c^{2} V$.