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Velocity - Loads of Confusion

  1. Sep 1, 2012 #1
    1. The problem statement, all variables and given/known data
    A baseball pitcher is known to throw a pitch with a speed of 105 miles per hour. In how many seconds will the pitch reach the catcher if the mound is 20 meters away? (assume 1600 m in 1 mile)


    2. Relevant equations

    v=d/t



    3. The attempt at a solution
    Idk how to convert yet... I always cheat and use an online one but I will be screwed for the test... So I'm going to give this a try...

    105 mi = 168000 m
    1 hour = 3600 s

    105 mi/h = 46.66 m/s

    The other part of the question I am totally confuse on.
    So i'll take the d/v=t?

    20/46.66=0.4286s?


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    1. The problem statement, all variables and given/known data
    A satellite travels at 4,000 km/hr. If the satellite travels 8 X 10^7 meters as it goes around once, how many hours are required for one orbit?



    2. Relevant equations

    v=d/t



    3. The attempt at a solution
    Honestly, I have never seen a problem with scientific notation except in math. I forgot how to do all that. So this one I honestly confuse on. How can I change that scientific notion to a number? I think that's what I need to do.
     
  2. jcsd
  3. Sep 1, 2012 #2
    The first one seems correct to me.

    All 8 x 10^7 means is 8 x 10 x 10 x10 x10 x10 x10 x 10. So you take 10 and add 6 zeros. 6 zeros, not 7 because 10^1 = 10.
    Now change it to km and you're good to go.
     
  4. Sep 1, 2012 #3

    rock.freak667

    User Avatar
    Homework Helper


    That would be correct.

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    You can just multiply out that number to convert it into a 'normal' number. For example if you are given 43.1 x 102, this would be the same as 4310 i.e. you actually multiply the 43.1 by the 102 (which is 100)
     
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