Hisaab Lagao

Understanding Power Units

Power is defined as the rate at which work is done or energy is transferred over time. Its SI unit is the Watt (W), which represents one joule per second. In addition to watts, power can also be expressed in larger or alternative units such as kilowatts, megawatts, gigawatts, horsepower, BTU per hour, foot-pound per second, calories per second, kilocalories per hour, and erg per second.

Conversion Formulas

• 1 kW = 1000 W
• 1 MW = 1,000,000 W
• 1 GW = 1,000,000,000 W
• 1 hp ≈ 745.7 W
• BTU per hour: 1 W ≈ 3.41214 BTU/h (thus, 1 BTU/h ≈ 0.293 W)
• Foot-pound per second: 1 W ≈ 0.737562 ft·lb/s (thus, 1 ft·lb/s ≈ 1.356 W)
• Calories per second: 1 W ≈ 0.239006 cal/s (thus, 1 cal/s ≈ 4.184 W)
• Kilocalories per hour: 1 W ≈ 0.860421 kcal/h (thus, 1 kcal/h ≈ 1.162 W)
• Erg per second: 1 W = 1e7 erg/s (thus, 1 erg/s = 1e-7 W)

Real-World Applications

• Electricity Generation & Consumption: Power plants, wind turbines, and solar panels often have their capacities expressed in kilowatts (kW), megawatts (MW), or even gigawatts (GW).
• Mechanical Systems: Engine power ratings are frequently given in horsepower (hp).
• Heating & Cooling: Appliances like air conditioners and heaters use BTU per hour as a measurement.
• Scientific Measurements: In physics and engineering, power might be expressed in units like watts, calories per second, or erg per second depending on the context.

Example Calculation

Consider a light bulb that consumes 60 watts of power. Using the conversion formulas:

Similar calculations can convert 60 W to other units like horsepower or BTU/h using the appropriate conversion factors.