Question: As you drive your car along a country road at night?

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Answer #1:

Let the retardation produced by the brakes is a m/s^2
=>By Ff = ma = coefficient of friction x m x g
=>a = 0.80 x 9.8 = 7.84 m/s^2
By v^2 = u^2 - 2as
=>0 = u^2 - 2 x 7.84 x 33.5
=>u = sqrt525.28 = 22.92 m/s = 51.27 miles/hour





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