What Is Work?
In physics, work has a specific meaning: force applied over a distance. If you push a box 5 meters with 10 newtons of force, you did 50 joules of work. Push against a wall that doesn't move? No work done — even if you're tired. Work requires movement.
What Is Energy?
Energy is the ability to do work. It comes in many forms: kinetic (motion), potential (stored), thermal (heat), chemical, electrical, and more. Energy can change forms but is never created or destroyed — just transformed.
The Work-Energy Connection
When work is done on an object, its energy changes by the same amount. Lift a book — you do work, and the book's gravitational potential energy increases. Drop it — gravity does work, converting potential to kinetic energy.
What Is Power?
Power is how fast you do work. Same job, less time = more power. A 100-watt lightbulb uses 100 joules per second. A 300-horsepower car engine produces 300×746 = 223,800 joules per second.
Energy in Sports
Cyclists with same fitness can have different power outputs — the stronger rider produces more watts. A sprinter needs high power output for a few seconds. A marathon runner needs moderate power for hours. Energy bars fuel the work; power determines performance.