C asked in Science & MathematicsPhysics · 4 weeks ago

A car skids to a stop with a deceleration of 4.1 m/s2. Due to the hard braking, the tires leave 51 m long skid marks on the pavement.?

a) Determine the speed of the car (in m/s) just before braking. 

b) How much time is required for the car to stop? 

1 Answer

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  • 4 weeks ago

    We can use conservation of energy

    a = F/m = µmg/m = µg = 4.1m/s²

    The kinetic energy is consumed by friction over 51m

    F*d = ½mV² = µmg*51 -----> V² = 2*µg*51 = 2*4.1*51 = 20.45²

    V = 21m/s <<<< a)

    b) 51 = 20.45*t - ½*a*t² at t = 5s <<<< b)

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