A copper wire with a circular cross-section has a mass of 1.35 g and a resistance of 0.790 ?. At 20°C, the resistivity of copper is 1.70 ? 10?8 ? · m and its density is 8,960 kg/m3. How long (in m) is the wire? How are density and mass related to volume? How is the volume of the wire related to its cross-sectional area and length? How are cross-sectional area and length related to resistivity and resistance? Be careful with units. m What is the diameter (in mm) of the wire? How is the length from part (a) related to volume and cross-sectional area? How is the volume related to mass and density? What is the cross-sectional area of a cylinder in terms of diameter? Be careful with units. mm