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Why do we treat the unit of pounds this way when doing Work=Force*dist. problems?

  1. Jan 28, 2006 #1
    I am reading over an explanation of Work in my calculus textbook (Early Trancendentals 5e - Stewart). The following example has me confused. Why are pounds treated as a force and not a mass?

  2. jcsd
  3. Jan 28, 2006 #2
    because lbs are a unit of force. the slug is the unit of mass for the english system
  4. Jan 28, 2006 #3
    The pound has actually been officially defined as a unit of mass, even though I believe it was used as a unit of force a long time ago. Nowadays the term pound-weight is used to refer to the gravitational force exerted by a pound, and if you notice the main question states "20-lb weight" to specify this, even though it neglects to be so specific in the rest of the text.
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