Compute each part of given question:
Question: A short cylindrical block of 6061-T6 aluminum, having an original diameter of 15mm and a length of 81mm, is placed in a compression machine and squeezed until the axial load applied is 6kN.
Part I: Determine the decrease in its length.
Part II: Determine the increase in its diameter.
Please show the work and steps for the calculation so I can understand what I'm doing. Thanks!