$${W_g = mgd\, \cos 0^{\circ} = (500\, \mathrm{kg})(9,8\, \mathrm{m/s^2})(12\, \mathrm{m})(1) \\ = 5,88 \times 10^4\, \mathrm{J} \approx \underline{\underline{59\, \mathrm{kJ}}}}$$