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Homework Help: 100 metre leap

  1. Mar 29, 2009 #1
    Suppose a person who wears a pair of super-bouncy shoes is able to cover a distance of 100 metres with one leap. Calculate the
    a) minimum initial speed he/she would have to achieve
    b) time taken for him/her to complete his/her leap with the above speed
    (Neglect air resistance.)

    2. Relevant equations

    The answer to the initial speed question is most probably unrealistic as it is humanly impossible to complete a 100 metre leap of that sort. I'm lost for an answer so any help would be greatly appreciated. Thanks!
  2. jcsd
  3. Mar 29, 2009 #2
    Yea, the shoe thing is kinda dumb.
    You should also find the jumping angle that corresponds to the minimum initial speed. This is a classic artillery problem.

    Work out the equations of motion for both axes; solve them at the landing point; eliminate time from the equations; convert to polar coordinates; solve for the initial speed; differentiate with respect to the jumping angle; and find where the derivative is zero.
  4. Mar 29, 2009 #3


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    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi quarktacular! Welcome to PF! :smile:
    mmm … it's the same question as "suppose you want to shoot a person out of a cannon 100 metres …" :wink:

    happier now? :smile:
  5. Mar 29, 2009 #4
    Re: Welcome to PF!

    Thanks for the welcome! Happier that at least someone gave the question a try but the thing is, it's not the same question. Trust me, it's not. My teacher keeps on telling me that it's do-able in the shoe context but seriously, I really don't know how he does it.
  6. Mar 29, 2009 #5


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    Staff: Mentor

    Re: Welcome to PF!

    Trust us - it is. It is the same combination of initial angle and speed.
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