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Homework Help: Massive Cable

  1. Mar 27, 2007 #1
    1. The problem statement, all variables and given/known data
    A massive steel cable drags a 20.0 kg block across a horizontal, frictionless surface. A 90.0 N force applied to the cable causes the block to reach a speed of 3.60 m/s in 2.40 s.
    What is the difference in tension between the two ends of the cable?

    2. Relevant equations

    F=ma
    a=v/t

    3. The attempt at a solution

    a=3.6/2.4= 1.5 m/s2

    90N=m*1.5
    m=60
    m(block)=20kg
    m(cable)=40kg

    F=40*1.5=60

    90-60=30

    Just looking at the numbers it doesnt look right

    Thanks all for your help
     
    Last edited: Mar 27, 2007
  2. jcsd
  3. Mar 27, 2007 #2

    PhanthomJay

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    Gold Member

    looks like you isolated the rope and came up with the NET force on the rope. Try drawing a FBD of the block. Or identify all forces acting on the rope.
     
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