The Origin of Horsepower
James Watt wanted a way to market his steam engines. He estimated that a pony could pull 22,000 foot-pounds of work per minute, then increased it to 33,000 for a "standard" horse.
The Watt (W)
In the SI system, Power is measured in Watts. 1 Watt is 1 Joule per second.
Conversion
- 1 Horsepower (hp) ≈ 746 Watts
- 1 Kilowatt (kW) ≈ 1.34 hp
Why It Matters
While we use HP for car engines, we use Watts for lightbulbs and computers. As we move to electric cars, you'll see more manufacturers quoting "Kilowatts" instead of "Horsepower."
Key Takeaways
- HP is a legacy imperial unit
- kW is the future of automotive power
- A hairdryer uses about 1,500 Watts (2 HP!)