14.1Work and Power
 Key Concepts
When does a force do work?
How are work and power related?
 Vocabulary
work
joule
power
watt
horsepower
 Reading Strategy
 Relating Text and Visuals   Print out the table shown at the right. As you read, look carefully at Figures 1 and 2 and read their captions. Complete the table by describing the work shown in each figure.
 

You are already familiar with the everyday meaning of work. Working at an after-school job, doing yard work at home, and completing your homework may all be common events in your life. In science, however, “work” means something very different.

Look at the weight lifter shown in Figure 1. He is exerting a large force in order to hold the heavy barbell over his head. You can tell from the look on his face that holding up the weight is hard work. However, a scientist would tell you that at this instant the weight lifter is actually doing no work on the nonmoving barbell. Read on to learn about the work that was done to lift the barbell overhead.

Figure 1  The weight lifter applies a large force to hold the barbell over his head. However, because the barbell is motionless, no work is done on the barbell.

 
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