Basic Engineering Practice
Basic Engineering Practice is the connective layer under every other topic: units, dimensions, balances, drawings, standards, and professional responsibility. Expect questions that are not conceptually hard but punish sloppy bookkeeping more than anything else.
Units and dimensions
Every calculation must be dimensionally homogeneous. In US customary units, pound-mass (lbm) and pound-force (lbf) are different quantities, related through g_c = 32.174 lbm·ft/(lbf·s²). Pressure may be gauge or absolute - always ask which; absolute = gauge + atmospheric. Flow rates, densities, and heat capacities often appear in mixed units, so convert everything to one system before computing.
Balances
Steady-state mass balance: input = output + accumulation, with accumulation zero at steady state. Component balances are per species; total balances are per mass. Industrial energy balances usually ignore kinetic and potential energy changes.
Drawings, tolerances, standards
Know how to read a title block, orthographic and section views, and basic GD&T symbols (flatness, position, perpendicularity). Understand clearance versus interference fits and tolerance stack-up. Standards and codes (ASME, ASTM, OSHA, ANSI) define what is acceptable; ethics questions test disclosure of risk and avoiding conflicts of interest.
Two classic traps
Rounding intermediate results, and mixing time bases (per hour versus per shift versus per year).
Worked example
Convert 5 gal/min of water (density 1 kg/L) to kg/s. Choose a conversion chain: 5 gal/min × 3.785 L/gal = 18.93 L/min ÷ 60 = 0.3155 L/s × 1 kg/L ≈ 0.316 kg/s. The chemistry is trivial; the only difficulty is not losing a factor in the chain.