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physics

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A tennis ball is thrown straight up with an initial speed of 19.5 m/s. It is caught at the same distance above the ground.
(a) How high does the ball rise?

  • physics - ,

    find time of flight:
    hf=ho+Vi*t-4.9t^2
    solve for t.

    Then solve for height at t/2

  • physics - ,

    d(up) = Vo*t + 0.5at^2,
    v=at,
    a = v/t,
    Substitute v/t for a in the 1st Eq:
    d(up) = Vo*t + 0.5(v/t)t^2,
    d(up) = 19.5t + 0.5 * (19.5)t,

    d(down) = 0.5 * 9.8t^2,

    d(up) = d(down),
    19.5t + 9.75t = 4.9t^2
    Solve for t:
    29.25t = 4.9t^2,
    4.9t^2 - 29.25t = 0,
    Factor out t:
    t(4.9t - 29.25) = 0,
    t = 0,
    4.9t - 29.25 = 0,
    4.9t = 29.25,
    t = 5.97 s.

    Solution set: t = 0, and t = 5.97 s.
    Select t = 5.97 s.

    d(up) = 19.5 m/s * 5.97 s + 9.75 m/s * 5.97 s = 174.6 m.

  • physics - ,

    SI unit of delta V/ delta t and dV/dt

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