a mountain biker cycling a trail traveling at 5.4 m/s begins to slow down when she notice a wooden bridge ahead has flooded. if she begins b

Question

a mountain biker cycling a trail traveling at 5.4 m/s begins to slow down when she notice a wooden bridge ahead has flooded. if she begins braking when she is 15.0 m from the bridge and comes to a stop just before reaching the bridge, how long did it take her to stop ?

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niczorrrr 5 years 2021-07-24T09:27:39+00:00 1 Answers 68 views 0

Answers ( )

  1. thienan
    0
    2021-07-24T09:29:05+00:00
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    Answer:

    t = 5.56 s

    Explanation:

    In order to calculate the time interval taken by the mountain biker to come to a stop, we will use third equation of motion and first find the deceleration:

    2as = Vf² – Vi²

    where,

    a = deceleration = ?

    s = distance = 15 m

    Vf = Final Velocity = 0 m/s

    Vi = Initial Velocity = 5.4 m/s

    Therefore,

    2a(15 m) = (0 m/s²) – (5.4 m/s)²

    a = – 0.972 m/s²

    Now, we use 1st equation of motion:

    Vf = Vi + at

    therefore,

    0 m/s = 5.4 m/s + (-0.972 m/s²)(t)

    t = (5.4 m/s)/(0.972 m/s²)

    t = 5.56 s

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