Convert Foot-Pounds per Pound to Kilojoules per Kilogram

The Foot-Pound per Pound (symbol: ft·lbf/lb) is a unit of specific energy. An imperial specific-energy unit equal to approximately 2.98907 J/kg (1 ft·lbf = 1.35582 J; 1 lb = 0.45359237 kg; ratio = 2.98907). ft·lbf/lb is a niche US-engineering unit used primarily in: ballistic kinetic-energy-per-mass calculations (E_k/m for projectiles, where US ballistics literature historically uses imperial mass for the projectile and ft·lbf for muzzle energy — a .308 Winchester 168gr bullet at 2,650 fps muzzle velocity has specific energy ~109,000 ft·lbf/lb), US-edition mechanical-engineering textbooks for mechanical strain-energy-per-mass calculations (Shigley, Norton, Hibbeler in dual-unit editions), and head-loss / hydraulic-energy specific calculations in US civil-engineering hydraulics where the natural unit is feet-of-head (1 ft of head of water ≈ 1 ft·lbf/lb specific gravitational potential). For typical engineering specific-energy scales (gasoline, batteries, structural-strain energy), the ft·lbf/lb numerical value is large and unwieldy — gasoline LHV is ~15.5 million ft·lbf/lb — so US engineers usually convert to BTU/lb for fuel work and reserve ft·lbf/lb for kinetic and elastic-strain applications. Convert ft·lbf/lb to J/kg by multiplying by 2.98907.

It belongs to the imperial measurement system.

Foot-Pounds per Pound are commonly used in fuel comparison, battery technology, and rocket propulsion.

The Kilojoule per Kilogram (symbol: kJ/kg) is a unit of specific energy. A metric specific-energy unit equal to exactly 1,000 J/kg. kJ/kg is the dominant working unit in thermodynamics for specific enthalpy h, specific internal energy u, and specific Gibbs/Helmholtz free energies (g, a) — all standard symbols in IAPWS-IF97 steam tables, NIST REFPROP property libraries, and CoolProp Helmholtz-energy fluid models. Reference values: saturated liquid water at 100°C (1 atm): h_f = 419.04 kJ/kg; saturated steam at same point: h_g = 2,676.05 kJ/kg; the latent heat of vaporization h_fg = 2,257.0 kJ/kg (the energy a low-pressure steam-heating system delivers when condensing). Refrigerant R-134a saturated liquid at 25°C: h_f ≈ 234.6 kJ/kg; saturated vapor: h_g ≈ 412.4 kJ/kg. Outside the US, food energy content on nutrition labels is reported as kJ/100g per EU Regulation 1169/2011 and Codex Alimentarius (typical: cooked white rice ~540 kJ/100g; olive oil ~3,700 kJ/100g; lean beef ~880 kJ/100g). HVAC design and combustion calculations per ASHRAE / VDI 4710 / EN 12831 routinely use kJ/kg for moist-air psychrometric enthalpy.

It belongs to the metric measurement system.

Kilojoules per Kilogram are commonly used in fuel comparison, battery technology, and rocket propulsion.