Understanding Power Measurements
Power is the rate at which energy is transferred or converted. The watt (W) is the SI unit, with kilowatts (kW) and megawatts (MW) used for larger quantities. Horsepower remains common for rating engines and motors, especially in the automotive industry. BTU per hour is used in HVAC systems for heating and cooling capacity.
Understanding power units helps when comparing appliance efficiency, sizing electrical systems, choosing HVAC equipment, or evaluating vehicle performance. For example, knowing that 1 HP equals about 746 watts helps when converting between electric motor and combustion engine specifications.
Frequently Asked Questions
How many watts are in one horsepower?
One mechanical horsepower equals approximately 745.7 watts or 0.7457 kilowatts. This conversion is commonly needed when comparing electric motor specifications with engine ratings. A 100 HP engine produces about 74.57 kW of power.
What is the difference between watts and kilowatt-hours?
Watts measure power (the rate of energy transfer), while kilowatt-hours measure energy (the total amount transferred over time). A 100-watt light bulb running for 10 hours consumes 1 kilowatt-hour (kWh) of energy. Your electricity bill charges for kWh consumed, not watts.