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Homework Help: Jumping Flea - Simple Kinematics

  1. Sep 22, 2009 #1
    1. The problem statement, all variables and given/known data

    A flea jumps straight up to a maximum height of 0.53 m. What is its initial velocity as it leaves the ground?

    2. Relevant equations

    3. The attempt at a solution

    Okay, I have three kinematic equations for constant acceleration I can use. All of them require the knowledge of some time interval, except for one, so I shall use that one since I'm not given any time info in this question.

    The equation says: [tex] {v_f}^2 = {v_i}^2 + 2a_s(s_f - s_i) [/tex]. Obviously f denotes final and i denotes initial.

    I know that my final velocity will have to be 0 since if the flea jumps to a maximum height of 0.53 m, he will start coming down after that. I also know that [tex] a_s = -9.8 [/tex]. Also, [tex] s_i = 0 [/tex] and [tex] s_f = 0.53 [/tex].

    Thus I have [tex] 0 = {v_i}^2 - 2(9.8)(0.53) \Leftrightarrow \sqrt[]{2(9.8)(0.53)} = v_i [/tex] and I will take the positive root to be my v_i.

    Is this correct?
  2. jcsd
  3. Sep 22, 2009 #2


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    Homework Helper

    Yes. It is correct.
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