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Homework Help: First timer

  1. Jan 27, 2005 #1
    A. If a person is thrown to maximum height of 23.8 ft, how long does she spend in the air during the toss? I figured out this answer. It is 2.43 seconds.

    B. Is the amount of time the person is above a height of 11.9 ft more that, less than, or equal to the amount of time the person is below a height of 11.9ft?
    Well, I know the answer is not equal. I don't not know what formulas to use. I am completely lost.

    C. Verify your answer to part B with some calculations.
    _____ seconds above 11.9 ft.
    _____ seconds below 11.9 ft.

    I worked part A using meters cause that what we have been doing in class. I need help with direction. I don't know where to begin for this second part. I thought of one thing but there was no formula to complete the second part so I got lost.
  2. jcsd
  3. Jan 28, 2005 #2


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    Science Advisor

    It would be better to show us howyou tried to do the problems as well as the answer you got.

    In problem A, the only difference between "meters" and "feet" is that, while the acceleration do to gravity is 9.81 m/s2, it is 32.2 feet/s2.

    I presume you are using the formula h= (-g/2)t2+ V0t+ h0 where V0 is the initial speed and h0 the initial height. You may be taking h0= 0.

    In that case, the maximum height is given by V02/g. Knowing the maximum height you can figure out what V0 is and then find the rest of the answers by solving the equation (-g/2)t2+ V0t= 11.9 for t.
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