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Calculating Distance Given Work and Forces

  1. Apr 8, 2014 #1
    1. The problem statement, all variables and given/known data

    A farmhand does 972 J of work pulling an empty hay wagon along level ground with a force of 310 N [23 degrees below the horizontal]. A frictional force of 280 N opposes the motion. The distance the wagon travels is
    a. 0.39 m
    b. 1.7 m
    c. 3.4 m
    d. 32 m
    e. 1.8 x 102 m

    2. Relevant equations

    W=FcosΘd
    Fnet=F1+F2

    3. The attempt at a solution

    W=Fd
    d=W/F
    d=972/(310cos23-280)
    d=180 m

    Apparently, the correct answer is c) 3.4 m, which works if you don't account friction, but I don't understand how that's correct.
     
    Last edited: Apr 8, 2014
  2. jcsd
  3. Apr 8, 2014 #2

    PhanthomJay

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    Science Advisor
    Homework Helper
    Gold Member

    You have divided the work done by the farmhand by the net force . If you are going to use the net force, you need to use the net work, not the work done by the farmhand.
     
  4. Apr 8, 2014 #3
    I was wrong
     
    Last edited: Apr 8, 2014
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