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physics

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A car is traveling 26 m/s when the driver sees a child standing in the road. He takes 0.8 s to react, then steps on the brakes and slows at 6.0 m/s2. How far does the car go before it stops?

  • physics - ,

    In .8 seconds he goes 26 * .8 meters
    then the problem is acceleration with initial speed Vo = 26 and acceleration = -6 m/s^2

    time to deacceletate to 0:
    v = Vo + a t
    0 = 26 - 6 t
    t = 26/6

    distance = .8* 26 + 26 t - (1/2) 6 * t^2

  • physics - ,

    The distance travelled during the "reaction time" t1 is
    X1 = V*t1 = 26 m/s * 0.8 s. = ?
    The time required to decelerate to 0 is t2 = V/a = 4.33 s
    The distance travelled while decelerating is the average velocity multipled by t2.
    X2 = (V/2)(V/a) = V^2/(2a) = ?
    Add X1 and X2 for the answer.

  • physics - ,

    Ah, good. I am off for a while :)

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