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E135 — Engineering Units, Conversions & Measurement — SI Prefixes, Temperature, Volume, Pressure & Dimensional Reasoning
Frozen parent: ENGINE.FUNDAMENTALS · 31 unique source families · 43 source occurrences · 8 verified teaching facts
This lesson teaches the reusable engineering principle behind the covered USCG source families. Original source stems are not reproduced as student content.
✓ U1 SI prefixes scale by powers of ten: kilo 10³, mega 10⁶, giga 10⁹, tera 10¹²; micro 10⁻⁶, nano 10⁻⁹, pico 10⁻¹².
✓ U2 Temperature conversion uses °F = (9/5 × °C) + 32 and °C = (5/9) × (°F − 32). Thus 80°C = 176°F and 122°F = 50°C.
✓ U3 Useful volume/weight conversions: 1 petroleum barrel = 42 U.S. gal; 1 ft³ = 7.4805 U.S. gal; 1 U.S. gal = 3.785 L; 1 kg ≈ 2.205 lb.
✓ U4 Useful length/pressure conversions: 1 m = 39.37 in and 1 bar ≈ 14.504 psi. Always identify whether pressure is gauge or absolute before converting.
✓ U5 Decimal-inch values can be converted to binary fractions: 0.625 in = 5/8 in; 0.234375 in = 15/64 in.
✓ U6 One kip is 1,000 lbf. Therefore 1,000 kips = 1,000,000 lbf = 500 short tons.
✓ U7 A protractor measures or lays out angles. In geometry and flow passages, divergent means the boundaries move farther apart in the direction considered.
✓ U8 Legacy plate-weight shorthand comes from steel density: a 1/2-in steel plate weighs about 20.4 lb/ft², hence the traditional '20-pound plate' approximation.
MEMORY: identify the physical quantity first, keep units visible through every step, and test whether the answer is dimensionally and physically reasonable.
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