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Quick Hello Then Question About Energy

  1. Apr 17, 2006 #1
    Hey,

    Im A Highschool Student; Nerd In Development; lol anyways iv'e come across this question in my Text Book and im not sure how to figgure it out; Can Someone PLEASE for the love of god tell me how the hell to do it

    Ok Heres The Status They Give You:

    Mass - 2kG
    Angle - 60
    Force - 100N
    Friction Force- 10N

    How long will it take to push this bucket over A Distance Of 5 Meaters?






    Back Of Book Answer= 0.71s


    Thanks
    ~Matty-Alan~
     
  2. jcsd
  3. Apr 17, 2006 #2

    Astronuc

    User Avatar

    Staff: Mentor

    One should show one's work first.

    Well, one needs to know the initial velocity, which may = 0 here.

    If there is a net acceleration, then the block is accelerating.

    The net acceleration is simply the net force divided by mass.

    Now, if one pushes the block, then friction opposes the pushing, i.e. the friction force is in the opposite direction of the pushing force.

    As for the pushing force, one must determine the component parallel with the displacement of 5 meters (presumably horizontal, but that is not given in the problem statement). Furthermore, with respect to the angle of 60°, it is not stated whether that is with respect of vertical or horizontal. And does the friction force of 10N apply simply to the mass of the block, or to the block plus whatever downward force one applies to the block.

    Then think of the equation which describes displacement as a function of time for constant acceleration. Hint, it is a quadratic relationship.

    This might help - http://hyperphysics.phy-astr.gsu.edu/Hbase/mot.html#mot1
     
    Last edited: Apr 17, 2006
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