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Homework Help: Newton sliding/falling block

  1. Oct 1, 2006 #1
    The problem is this: There are two blocks of unknown masses M1 and M2. M1 is sitting on a frictionless table and M2 is attached to m1 by a massless string and is hanging over the edge over a pulley. If m1 is four times more massive than m2, how far will m1 travel in 0.633 seconds?
    So far I've gotten
    a= (m2/m1+m2)g .
    I replaced m1 with 4*m2, and then simplified the equation to give me
    a=(1/5)g
    a=(1/5) 9.8
    a= 1.96 m/s^2.

    Once I had the acceleration, I then used the fact that a=v/t to give me the velocity, and then I multiplied the velocity by the time to give me distance.
    a=v/t
    1.96=v/.633 sec
    v=1.24m/s
    I then multiplied that by the time in order to give me the distance.
    v*t= 0.785 m

    I entered this into the homework on the internet and it says I'm wrong, I don't know what else to do? Can anyone help me on where I messed up?
    thanks
     
  2. jcsd
  3. Oct 1, 2006 #2
    it's not a=v/t, but a=dv/dt.

    you did solve for v correctly and a correctly though and you almost have the right answer. the error is in the last part of your work.

    what does (velocity)(time)=distance mean?
     
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