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Homework Help: Work Energy Power Problem?

  1. May 7, 2012 #1
    1. The problem statement, all variables and given/known data

    A 5.0 kg box is sliding across the floor at 2.0 m/s when it is accelerated to 8.00 m/s in 1.8 s. If the coefficient of friction is .220 how much power is required to accelerate the box?

    m = 5.0 kg vi= 2.0 m/s vf = 8.00 m/s change in time = 1.8 s coefficient = .22

    2. Relevant equations

    Power = Work (W) / change in time (t)
    W= Fnetd

    Fnet = ma
    3. The attempt at a solution
    P= w/ t

    w= FNetd

    Heres my issue. I know Fnet(net force) = ma, which i can easily calculate. The problem is where do i use the coefficient of friction they gave me. Do I need to use it, if i already have Fnet?
  2. jcsd
  3. May 7, 2012 #2
    You find the force acting against the box and take that away from the force required to accelerate the box to get the net force.
    Last edited: May 7, 2012
  4. May 7, 2012 #3
    So what do i use for the w= Fnetd calculation?
  5. May 7, 2012 #4
    D= distance the box moved after acceleration
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