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Homework Help: How to calculate time for ticker tape to move from a point to another point?

  1. Feb 8, 2012 #1
    1. The problem statement, all variables and given/known data
    Question: How to calculate time for ticker tape to move from a point to another point?
    "The ticker-tape timer consists of a steel strip which vibrates 50 times a second and makes 50 dots a second on a paper being pull through it."

    2. Relevant equations

    3. The attempt at a solution
    the dots on the ticker tape are increasing in distance, how to count the time taken for it to move from a point to the other? I have no idea what to begin with...
  2. jcsd
  3. Feb 8, 2012 #2
    Start with this:

    The distance between dots (any 2 dots or more) corresponds to what? What does it mean to measure the distance between these dots?

    If you have 50 dots per second, how many seconds does 1 dot correspond to?
  4. Feb 8, 2012 #3
    1 dot correspond to 0.02 sec, but how do I calculate for those that are further apart from the constant ones ( constant distance between the dots)
  5. Feb 8, 2012 #4
    Remember that the more dots you measure, the more precise your average measurement will be. Now, you know the time it takes for two dots to be drawn, if you measure the distance between any two dots, you know that it took 0.02s to cover that distance. What can you say about the speed of the tape? For the ones that seem further than others, calculate them in the same way.
  6. Feb 8, 2012 #5
    Wouldn't the speed and distance be different for dots that are further away from each other? that would be 2 unknown variables which I don't know how to solve...

    P.S. it is in an increasing acceleration
  7. Feb 8, 2012 #6
    [STRIKE]Oooo, regardless how far dots are apart from each other, the time taken would still be 0.02s from a dot to the other? am i right?[/STRIKE]

    EDIT: do we use a ruler to measure? on the ticker tape
    Last edited: Feb 8, 2012
  8. Feb 8, 2012 #7
    Yes use a ruler, and yes if the dots are increasing in distance then there is an acceleration, you have to account for that.
    How is acceleration linked to velocity? (In terms of formulas)
  9. Feb 9, 2012 #8
    Yeah, i figured out how to do it :smile:

    Thanks guys!
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