General Engineering and Applied Sciences: Physics, Chemistry, and Engineering Economy
Scope of the section
GEAS bundles the non-major fundamentals: physics (kinematics, Newton's laws, work-energy, momentum, thermodynamics, waves, optics), chemistry (gas laws, stoichiometry, solutions, pH, electrochemistry), statics and strength of materials, fluid mechanics, engineering materials, engineering economy, and basic computer and ethics items. Questions are usually one- or two-step applications, so recognizing the governing formula matters more than derivation.
Traps that cost points
- Temperature scale in gas laws. PV = nRT requires kelvin: T(K) = T(°C) + 273.15.
- Gauge versus absolute pressure. P_abs = P_gauge + P_atm.
- Prefixes and density units. 1 kPa = 1000 Pa, 1 MPa = 10⁶ Pa; 1 g/cm³ = 1000 kg/m³.
- Work versus power. Work is in joules, power in watts; 1 hp = 745.7 W.
- Economy formulas. Simple versus compound interest, ordinary annuity versus annuity due (the due form has one extra compounding period), and the four depreciation methods - straight-line, sinking-fund, sum-of-years-digits, declining-balance.
- Efficiency. η = useful output ÷ total input, never output ÷ output.
Worked example
A Carnot engine operates between 500 K and 300 K. Its efficiency is
η = 1 − T_L/T_H = 1 − 300/500 = 0.40, or 40%.
The trap is feeding Celsius values into the formula: 227 °C and 27 °C must be converted first, or the answer comes out wrong. Rule of thumb: every temperature ratio in thermodynamics is a ratio of absolute temperatures, and a ratio of absolute temperatures is the same in °C only by coincidence - never assume it.