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Homework Help: Average speed of a boat

  1. Jan 31, 2009 #1
    1. The problem statement, all variables and given/known data
    A boat moves 15.0 km across a lake in 30.0 min. What was the average speed of the boat in kilometers per hour?

    2. Relevant equations
    average speed: d/t

    3. The attempt at a solution
    ok since it is asking kilometers per hour that is the part tha confuses me.
    i mean i believe that it is 15.0 km/30.0
    but it is asking for hour...
    sooo that where i get lost.
  2. jcsd
  3. Jan 31, 2009 #2


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    Homework Helper

    That's what it did in 30 min.

    How much would it do in an hour.
  4. Jan 31, 2009 #3
    oh so then i multiply that times 2?

    or would i do 15.0/60?
  5. Jan 31, 2009 #4
    ok no..that doesn't make sense :S
  6. Jan 31, 2009 #5
    If it goes x km in thirty minutes and keeps the same speed, wouldn't it go the same distance in the next thirty minutes?
  7. Jan 31, 2009 #6
    ooh so then its the same..
  8. Jan 31, 2009 #7


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    Science Advisor

    Your 15km/30 is lacking one thing: Units on the 30. The 30 is in minutes, so this division would give you km/minute.
  9. Jan 31, 2009 #8
    hm, but it is asking for kilometers per hour.

    gosh sorry i'm soo ugh for this.
  10. Jan 31, 2009 #9
    30 min is ½hour, right?

    It goes 15km in ½hour - how much in 1 whole hour?
  11. Jan 31, 2009 #10
    oh so then it is 30km/h?
  12. Jan 31, 2009 #11
    Yep, that's it.
  13. Jan 31, 2009 #12
    wow! thank you so much!
    i truly appreciate it!
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