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Homework Help: Missing gravity and kinetic friction

  1. May 27, 2010 #1
    1. The problem statement, all variables and given/known data

    What is the network done on the car during the time interval?

    Mass = 75,000kg
    Vi = 0
    vf = 111.11m/s^2
    t = 2.5s
    ∆x = 138.8875m


    2. Relevant equations

    W= F∆X

    ∆KE = (1/2)(m)(v)^2

    W = ∆KE

    3. The attempt at a solution

    ∆KE = 1/2(75000kg)(111.11m/s)^2
    ∆KE = 463953703.8j

    And since W=∆KE
    W = 463953703.8j

    Is this right? I am wondering if I am missing gravity and kinetic friction somewhere?

    Thanks
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 27, 2010 #2

    kuruman

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Re: Work

    Your method of calculation is correct - I did not plug in the numbers to see if you did that part correctly. I cannot help wondering what kind of car has mass 75,000 kg (75 tons) and is able to go from zero to 111 m/s (250 miles per hour) in 2.5 s.
     
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