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Extended Experimental Investigation.

  1. Nov 22, 2007 #1
    My teacher has given me a Extended Experimental Investigation to do that requires physics. I know a bit about it (the very basics) and i'm not sure on a few things about it. For my task I have forgotten to measure my displacement and I was wondering if anybody knew a way I could still find it. I'll write down what i've got so far (I'm using a ticker timer and my task is to investigate the effect of a load on displacement, velocity and acceleration on a trolley):

    I have a graph showing my section of the tape, mass, time, length, Average acceleration of 5 intervals, Average acceleration for section and Average Acceleration for tape.

    If anybody could help me, that would be very much appreciated.

    Thanks,
    Aaron.
     
  2. jcsd
  3. Nov 22, 2007 #2

    andrevdh

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    The experimental data need to be analyzed since it is an experimental investigation. It seems you have got only the data for the average acceleration of the tape. Do you still have access to the tape itself?
     
  4. Nov 22, 2007 #3
    No, the tape is not on me at the moment, but I have the measurements of it written down if that helps. =)
     
  5. Nov 22, 2007 #4

    andrevdh

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    What measurements do you have?
     
  6. Nov 22, 2007 #5
    Tape 1.
    Sections:
    1)2cm
    2)5.7 cm
    3)9.8 cm
    4)14.0 cm
    5)17.4 cm
    6)21.0 cm
    7)19.4 cm

    Tape 2.
    Sections:
    1)2.1 cm
    2)6.1 cm
    3)10.3 cm
    4)14.4 cm
    5)18.3 cm
    6)19.8 cm
    7)20.4 cm

    Tape 3.
    Sections:
    1)2.1 cm
    2)5.5 cm
    3)9.9 cm
    4)14 cm
    5)14.2 cm
    6)20 cm
    7)19.8 cm

    Tape 4.
    Sections:
    1)1.3 cm
    2)5 cm
    3)9.2 cm
    4)13.7 cm
    5)17.3 cm
    6)21.1 cm
    7)20.7 cm

    Tape 5.
    Sections:
    1)2.5 cm
    2)6.8 cm
    3)11 cm
    4)15.5 cm
    5)19.6 cm
    6)20.4 cm
    7)19.4 cm

    If it helps, I had the trolley run down a ramp but i'm also unsure of the angle degree, sorry. This is the first time i've ever done physics because i've missed half of this semmester because I was in hospital. I'm not lazy. =P
     
  7. Nov 22, 2007 #6

    andrevdh

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    So you kept the angle constant and recorded the same motion five times?
     
  8. Nov 22, 2007 #7
    Yep. But I was increasing the mass each time.

    Tape 1: 0g
    Tape 2: 250g
    Tape 3: 500g
    Tape 4: 750g
    Tape 5: 1kg
     
    Last edited: Nov 22, 2007
  9. Nov 22, 2007 #8

    andrevdh

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    I assume the the measurements above in each section is the distances between successive marks on the tape?
     
  10. Nov 22, 2007 #9
    Yeah I have divideded the dots into groups of 5 intervals and measured them in cm.
     
  11. Nov 22, 2007 #10

    andrevdh

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    So each distance (in cm) is the "length" of a group of five dots?
     
  12. Nov 22, 2007 #11
    That is correct.
     
  13. Nov 22, 2007 #12

    andrevdh

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    We seem to be getting somewhere. The average acceleration values that you've got are then for each such group of five dots? How/from where did you get those values?
     
  14. Nov 22, 2007 #13
    "The average acceleration values that you've got are then for each such group of five dots?" I dont mean do be annoying or anything, but what do you mean?

    I dont think I actually mentioned this but i'm using a ticker timer. My ticker tape is roughly 1m long on each of the tapes.

    I used the ticker time and got all the dots on my ticker tape, then I divided the dots on the tape into groups of 5 intervals each (giving me sections 1-7 on each tape).
     
  15. Nov 22, 2007 #14

    andrevdh

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    Well this is what you said in your first post:

     
  16. Nov 22, 2007 #15
    I'm not really following, sorry. I'm just getting really confused now.

    I'm not sure what you meant about the average acceleration and i'm also not sure as to why you quotes what I said.

    I attatched my work so far if you want to have a look at it. I'm probably confusing you ALOT.
     

    Attached Files:

  17. Nov 22, 2007 #16

    andrevdh

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    No, you are not confusing me, but your document could take quite a while to get approved before I can view it. I am not sure if you want to wait that long. I just thought that you somehow got the accelerations since you mentioned it in your first post. You do not know by any means what the lenght of each time interval of the ticker timer is? Usually it is the rate at which the local electric power are running - 50 or 60 hertz.
     
  18. Nov 22, 2007 #17
    The average acceleration for tape 1:
    Sections:
    1)200
    2)370
    3)410
    4)420
    5)340
    6)360
    7)-160

    The average acceleration for the whole of tape 1 is 277.14
     
  19. Nov 22, 2007 #18

    andrevdh

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    So the question is again: How did you arrive at these numerical values and what are the units for the acceleration? Maybe show how one of these values were calculated.
     
  20. Nov 22, 2007 #19
    Well I have 0.1 seconds for time (cant remember how I got it but it was divided by something off memory). The length of my first section of the first tape is 2cm. From that i've gotten average acceleration of 200cm/s. I multiplied the 2cm by something to get the 200cm/s. I done it a while ago and reading over it, I have no clue how i've done it. =S

    I think I went 0.1s x 10 = 1s. Then 2cm x 10 = 20cm/s. Then I think i've went x 10 again to get 200cm/s for my average acceleration.
     
    Last edited: Nov 22, 2007
  21. Nov 22, 2007 #20

    andrevdh

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    I think I know how you got there....

    Your power is running at 50 hertz. This means that the ticks are

    [tex]\frac{1}{50} = 0.02\ seconds[/tex]

    apart. So that elapsed time for five ticks should actually be

    [tex]4 \times 0.02 = 0.08\ seconds[/tex]

    but you took it as

    [tex]5 \times 0.02 = 0.1\ seconds[/tex]

    so you did for the acceleration

    [tex]\frac{2}{0.1 \times 0.1} = 200 cm/s^2[/tex]
     
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