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Math Help - Need Physics help pls

  1. #1
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    Need Physics help pls

    If a 75-kg sprinter can accelerate from 0.3 m/s to a speed of 10 m/s in 2 s, what average power is generated?

    a. What is the Change in Kinetic Energy of the sprinter?
    b. What is the WORK DONE by the sprinter?
    c. How much power is does the sprinter generate during this process?

    Need help with these equation
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  2. #2
    MHF Contributor MarkFL's Avatar
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    Re: Need Physics help pls

    a) \Delta K=K_f-K_i=\frac{1}{2}m\left(v_f^2-v_i^2 \right)

    b) Use the work-energy theorem.

    c) Power is the time rate of work.
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  3. #3
    fkf
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    Re: Need Physics help pls

    Quote Originally Posted by Louisana1 View Post
    If a 75-kg sprinter can accelerate from 0.3 m/s to a speed of 10 m/s in 2 s, what average power is generated?

    a. What is the Change in Kinetic Energy of the sprinter?
    b. What is the WORK DONE by the sprinter?
    c. How much power is does the sprinter generate during this process?

    Need help with these equation
    The unit of power is Watt (Joule/second).

    The initial kinetic energy is
    E_ki = mv^2/2 => E_ki = 75*0.3^2/2

    The final kinetic energy is
    E_kf = mv^2/2 => E_kf = 75*10^2/2

    The change in kinetic energy is then
    E_kf-E_ki = ...

    The work done by the sprinter is the same as the energy turnover (is that correct English?)

    We then have that the sprinter generates a power equal to the difference in kinetic energy over a period of time, in this case 2 seconds.
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  4. #4
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    Re: Need Physics help pls

    Exactly what kind of help do you need? Apparently you are taking a course in physics involving kinetic energy. If so you should know that the kinetic energy of a body of mass m, at speed v, is (1/2)mv^2. Okay, you are given the mass and initial and final speed so what were the initial and final kinetic energies? Since "work" increases energy, the amount of work done is the change in energy. And "average power" is work done divided by the time it took to do the work.
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  5. #5
    MHF Contributor MarkFL's Avatar
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    Re: Need Physics help pls

    You should post your question in a new topic, and give the complete problem.

    edit: never mind...I now see you are only here to pollute our forum with spam.
    Last edited by MarkFL; November 9th 2012 at 02:06 AM.
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