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Homework Help: What is the minimum work needed to push a car

  1. Oct 31, 2006 #1
    What is the minimum work needed to push a 1025 kg car 200 m up along a 17.5° incline?

    (a) Ignore friction.
    I got 604117.9512J
    (b) Assume the effective coefficient of friction retarding the car is 0.40?
    how do I get this one?
     
  2. jcsd
  3. Oct 31, 2006 #2
    for a) what does work do? What aspect of the car does it change??? How do you calculate the work done then?
     
  4. Oct 31, 2006 #3
    Do I need to know Work in this case?
     
  5. Oct 31, 2006 #4
    you can calculate work

    work changes the energy
     
  6. Oct 31, 2006 #5
    Use the work-energy theorem:
    [tex] W= \Delta K + \Delta U + |W_{fric}|[/tex]
    To find the minimum work, push the block slowly so that [tex] \Delta K=0[/tex]. In (a), W_fric = 0. What is W_fric in (b)?
     
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