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Homework Help: Basic Forces- Just seeking a simple answer

  1. Apr 26, 2010 #1
    1. The problem statement, all variables and given/known data

    Given that the mass of a car is 1000kg, gravitational field strength = 10N/kg

    Find the force required to just lift the book up at a constant speed.


    3. The attempt at a solution

    Constant speed, Accel. = 0

    W = mg
    = 1000kg * 10N/kg
    = 10,000N

    Therefore force needed to just lift the book is 10,000N?

    However, by the newton's law, in balanced forces, object at rest will remain at rest... So the car was originally at rest, will it be lifted up by 10,000N?
     
  2. jcsd
  3. Apr 26, 2010 #2
    is it book or car? .. can you please clarify your question..
     
  4. Apr 27, 2010 #3
    sorry, its a car
     
  5. Apr 27, 2010 #4
    your answer is correct .. And regarding your last question, i believe that as long as the car is lifted at constant speed we can not say that there is a net force upward, since if a=0 this implies F=ma=0 N .. What we can say is that we have two forces one upward and the other downward with a value of 10,000N.. When you say it is lifted up with 10,000N it is as you are saying that the net force is 10,000N upward ..

    Im not sure whether the other members would agree with my point, but I believe it is that way ..
     
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