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HelP Gr 10 guy in Physics 11 AHH PROblEM NEEDING TO BE SOLVED

  1. Sep 14, 2004 #1
    OK Physics Help Plz

    1st question

    A person, resting in a boat, notices that 16 waves pass the boat every 38 s.
    How many waves wouldf pass the boat in 55 s.






    2nd question

    If 180 waves wash up ona shore in 1.00 h, what is the time between waves, in seconds?




    3rd question
    A ticker tape timer makes 360 dots in 6.0s. How long does it take to make six dots?





    THanks for the Help guys i appreciate it SO MUCH :cry:
     
  2. jcsd
  3. Sep 14, 2004 #2

    cepheid

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    Somebody's going to say this, so I might as well. Please show us your work, what you have so far. The guys on the site don't mind putting you in the right direction or correcting some work you submit, but they won't do your HW for you.

    Having said that...hints.

    1. What is the rate at which waves pass the boat (i.e. how many waves per second?). Once you know that (and assuming this frequency remains constant), how would you figure out how many total waves pass by in a given time interval?

    2. Same concept as before. This time you want period instead of frequency. How are they related?
     
    Last edited: Sep 14, 2004
  4. Sep 14, 2004 #3
    i figured out that like 16 divided by 38 would equal the frequency and that is 0.42 and that the period is 38/16=2.4s but how do i build up on that
     
  5. Sep 14, 2004 #4
    ok for question one for far i put 55 waves x 2.4 s = 132 waves .. hopefully it is correct and do i have to change anything due to significant figures ?
     
  6. Sep 14, 2004 #5
    uh oh i did it wrong ...
     
  7. Sep 14, 2004 #6
    ok i did it again and this time i put 0.42x55= 25 waves Now am i right?
     
  8. Sep 14, 2004 #7
    aw gee its 23.1? i think its too dark in this room +__+
     
  9. Sep 14, 2004 #8
    Yes, you are right (23.1). If you can do this, you can surely do Questions 2 and 3. For Q2, note that 1 hour = 3600 s. For Q3, remember that the time taken to make 6 dots will be less.
     
  10. Sep 14, 2004 #9

    cepheid

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    I think we made some progress by PM. Let me know if there's anything else.
     
  11. Sep 14, 2004 #10

    HallsofIvy

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    Try keeping track of the units: 16 waves in 38 seconds is 16/38= 0.42 "waves per second". Okay, now how do find how many waves in 55 seconds?

    2nd question: One hour = 60 minutes= 3600 seconds. 180 waves wash up ona shore in 1.00 h= 3600 seconds so you could form either of two fractions:
    180 waves/ 3600 seconds or 3600 seconds/ 180 waves. The question asks "time between waves, in seconds?" so which do you think is right?


    3rd question
    "A ticker tape timer makes 360 dots in 6.0s. How long does it take to make six dots?"
    Okay, that's 6.0/360 "seconds per dot". How many seconds for 6 dots?
     
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