(a) A version of the support platform in Figure 2.25 is required for aerospace use, for which its electrical conductivity should be as high as possible combined with minimum weight. Assume that all the section thicknesses should have the same value, h, so that the part volume can be expressed approximately in the form V = Co h, where Co is a constant. Using electrical resistivity, y (Q - cm), and density, p (g/cm3), determine the derived parameter which represents electrical current flow/weight. (b) Use this parameter to compare different metals: gold, silver, copper & aluminum (present results in a clear tabular form). Refer to materials handbooks for resistivity and density data or use web material databases such as www.matweb.com. Hint: Assume a voltage, V, is applied across the conductive paths through the legs (vertical struts) of width, w, thickness, h, and length, 1 (ignore the horizontal bars). Further assume, w and I are fixed by the design. Thus, h needs to change with the change of material to obtain the required value of conductivity. Write an expression for current flow, I, in terms of these parameters and the variable thickness, h. Use this with an approximate expression of part weight to obtain the required result. Figure 2.25 Electrical instrument support platform