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Energy Problem Involving Spring Force

  1. Apr 7, 2009 #1
    1. As a 1.7×104 jet plane lands on an aircraft carrier, its tail hook snags a cable to slow it down. The cable is attached to a spring with spring constant 6.0×104 . If the spring stretches 31 to stop the plane, what was the plane's landing speed? (Answer in m/s)



    2. Relevant equations
    Fsp=k[tex]\Delta[/tex]s where k is the spring constant and [tex]\Delta[/tex]s is the change in position.
    Also possibly the Equation for kinetic energy
    K=1/2mv2
    And also posibly
    vf2=v i2+2a[tex]\Delta[/tex]s
    where v is velocity and a is acceleration

    Also the conservation of energy and momentum equations are possible along with f=ma




    3. The attempt at a solution

    I found the spring force to be 1860000 N and then I lost where to go exactly. I tried to use F=ma to find acceleration, and then use kinematics (vf2=v i2+2a[tex]\Delta[/tex]s) because v final should be zero, but I got the wrong answer. My incorrect answer was 82m/s.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 7, 2009 #2

    LowlyPion

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    Homework Helper

    Maybe consider using the KE and PE of spring?

    1/2*m*v2 = 1/2*k*x2

    v2 = k*x2/m = 60,000*312/17,000
     
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