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A car is moving at 80km/h is subjected to a uniform retardation and brought to rest in 70seconds.find retardation and distance travelled by the car before it comes to rest.

  • physics -

    vf=vi+a*t
    but a= force/mass

    vf=vi+force*time/mass

    So, you need the mass of the car to determine force of retardation.

  • physics -

    Vo = 80,000m/3600s = 22.22 m/s.

    V= Vo + a*t = 0.
    22.22 + a*70 = 0,
    a = -0.317 m/s^2.

    V^2 = Vo^2 + 2a*d = 0.
    (22.22)^2 - 0.63779 4d = 0,
    d = 779 m.

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