1. You have a block of steel 10cm x 10cm x 4cm. You drill 81 holes through the 4cm dimension of the block. The holes are on a 9x9 square grid with 1 cm spacing. The diameter of each hole is 1mm. (a) Determine the porosity and permeability of the block. (b) In a second block, you drill a single larger-diameter hole, so that the porosity is the same as your first block. What is the diameter of the hole? What is the permeability of the second block? (c) Does the grid pattern (first block) make a difference? Explain.