physics

A car is moving at 90 km/h when the driver notices an animal that is about to cross the road 100 m away and he decides to apply the brakes. The reaction time of the driver is 0.3 s.
Calculate the acceleration of the car when it stopped and the time taken from the time the driver noticed the animal to the time the car stopped

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  1. Vo = 90km/h = 90000m/3600s. = 25 m/s.


    V^2 = Vo^2 + 2a*d. Solve for a.
    a = (V^2-Vo^2)/2d = (0-(25^2)/200 = -3.125 m/s^2.

    t = 0.3 + (-Vo/a) = 0.3 + (-25/-3.125) =
    8.3 s.

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    posted by Henry

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