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Homework Help: Force and acceleration

  1. Apr 11, 2005 #1
    Hi all!

    I'd like to know fi anybody can help me out with this, I just need some info so I can do it by myself.. formulas or something.

    I have a disk (looks like a hockey puck) sliding on an air table wich is elevated with an angle of 5°. [weight of the disk: 0,558g] Every 0,1s, the disk makes a mark on a sheet of paper.

    I need to make a table of the position (y) and time (x) and another one with average speed and time spent between each points (wich is 0,1s) .. anyone know how to do that?

    Thanks for the help ;)
    - Alex

    ps: Sorry, I'm not too use with physic english terms.. :uhh:
    Last edited: Apr 11, 2005
  2. jcsd
  3. Apr 11, 2005 #2
    What is the lenght of one mark?
    Last edited: Apr 11, 2005
  4. Apr 11, 2005 #3
    the lenght is smaller between each points, here's what it looks like:

    Between Points...
    [1-2] 7,0 cm
    [2-3] 6,2 cm
    [3-4] 5,9 cm
    [4-5] 5,0 cm
    [5-6] 3,9 cm
    [6-7] 3,3 cm
    [7-8] 2,3 cm

    There we go ;) sorry I didn't mention this in the first post
  5. Apr 11, 2005 #4
    So between point 1 and 2, v1=0 and v2=2d+v1/t. Vavg: v2-v1/2.

    So I'll only do 1-2:

    v2=2(0.07)+0/0.1=1.4 m/s
    vavg=1.4-0/2=0.7 m/s
    Last edited: Apr 11, 2005
  6. Apr 11, 2005 #5
    Allright, I got it. Thanks alot ;)
  7. Apr 11, 2005 #6
    The problem is not true when checking:

    vf^2=2(0.07)sin5*g=0.35 m/s
    so vf=1.15 m/s

    and vavg=0.35+0/2=0.175 m/s

    The time isn't 0.1 s unless the coefficient of friction is 16.37 (wich no matter has).
    Last edited: Apr 11, 2005
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