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Homework Help: Standard mech Q

  1. Jan 16, 2006 #1
    hi this is a simple question but for some reason it's not clicking.

    A ball of mass 0.5kg is pulled across a smooth horizontal floor by a horizontal string attached to the dog. The tension in the string is 0.75N. Calculate the acceleration produced. Given the ball starts from rest, determine how far it will move in 2 seconds.

    I know how to do the second part but some help would be appreciated on the first bit please.

    F resultant = F - T
    F-0.75 = ma
    a = F- 0.75 /0.5
    errm...and then?
     
  2. jcsd
  3. Jan 16, 2006 #2
    Is the ball rolling? or is it dragging across the floor? Some coeffeciant of friction would be needed if it was being dragged.
     
  4. Jan 16, 2006 #3
    oops sorry i didn't read the question properly, it's actually a bag and it's being pulled across.
     
  5. Jan 16, 2006 #4

    Doc Al

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    Staff: Mentor

    Since the floor is smooth, I would assume that the only horizontal force acting on the bag is the tension in the string, which is given.
     
  6. Jan 16, 2006 #5
    Of course, because then the acceleration = 1.5 which is correct.

    Thanks!
     
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