What does it mean if a light bulb uses 60 watts? — B, Los Angeles 

The watt is a unit of power, equivalent to the joulepersecond. One joule is about the amount of energy it takes to raise a 12 ounce can of soda 1 foot. A 60 watt lightbulb uses 60 joulespersecond, so the power it consumes could raise a 24can case of soda 2.5 feet each second. Most tables are about 2.5 feet above the floor. Next time you leave a 60watt lightbulb burning while you're not in the room, imagine how tired you'd get lifting one case of soda onto a table every second for an hour or two. That's the mechanical effort required at the generating plant to provide the 60watts of power you're wasting. If don't need the light, turn off lightbulb!