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Kinematics: Velocity and Distance of a Tennis Ball

  1. Oct 10, 2009 #1
    1. The problem statement, all variables and given/known data

    A ball approaches a tennis racquet with a velocity of [tex]30ms^-^1[/tex]. The racquet gives it an average acceleration of [tex]5000ms^-^2[/tex] for [tex]0.02s[/tex] in the opposite direction to it's initial velocity. What is the velocity of the ball after leaving the racquet and how far does the ball travel while undergoing this acceleration?

    2. Relevant equations

    Where: s=displacement, u=initial velocity, v=final velocity, a=acceleration, t=time

    [tex]
    v=u + at
    [/tex]

    [tex]
    s=(1/2)(u+v)t
    [/tex]

    [tex]
    v^2=u^2+2as
    [/tex]

    [tex]
    s=ut+(1/2)at^2
    [/tex]

    3. The attempt at a solution

    What confuses me about this question is the wording used. So forgive me if it confuses you too but I've written the question the same as it was wrote. I don't want to say specifically what part of the question is confusing as I think it'd be best for you to interpret the question and answer without me influencing you.

    So can somebody answer this 2 part question? I'd be happy to show how I think it's worked out but as I said earlier, I think the question can be interpreted in a number of ways so I'll wait for an answer before I give my interpretation.

    Thanks a lot, I really appreciate all the feedback.
     
  2. jcsd
  3. Oct 10, 2009 #2
    From the way i see it i will solve this using impluse-momentum theory what's your approach? :biggrin:
     
  4. Oct 10, 2009 #3

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Welcome to PF Fedor.

    Hey, just FYI, we require students to show their attempt at solving a homework problem before giving help with the solution.

    That being said, I'm guessing the confusion has to do with the question, "how far does the ball travel"? Do they simply mean the ball's displacement, or do they mean the total distance covered ... which would be different if the ball happens to reverse direction.

    If this is a problem to be handed in, you might just work out both answers, and include a note to the grader that you found the wording of the question ambiguous.
     
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