Suppose a car is traveling at 19.3 m/s, and the driver sees a traffic light turn red. After 0.236 s has elapsed (the reaction time), the driver applies the brakes, and the car decelerates at 8.00 m/s2. What is the stopping distance of the car, as measured from the point where the driver first notices the red light?

Respuesta :

Answer:

The total distance covered is [tex]D = 27.76 \ m[/tex]

Explanation:

From the question we are told that

   The initial speed  of the car is  [tex]u = 19.3 \ m/s[/tex]

   The time taken before breaks where applied is  [tex]t = 0.236 \ s[/tex]

     The deceleration is  [tex]a = 8.00 \ m/s^2[/tex]

The first distance covered before break was applied is mathematically evaluated as

      [tex]d = u * t[/tex]

substituting values

      [tex]d = 19.3 * 0.236[/tex]

      [tex]d = 4.484 \ m[/tex]

The distance covered after break has been applied is mathematically evaluated using the equation f motion as follows

      [tex]v^2 = u^2 - 2 as[/tex]

The negative sign is because the car is decelerating  and the final velocity is zero

       [tex]u^2 = 2as[/tex]

=>    [tex]s = \frac{u^2}{2a}[/tex]

substituting values

       [tex]s = \frac{19.3^2}{2(8)}[/tex]

       [tex]s = 23.28 \ m[/tex]

The total distance covered is  

    [tex]D = d+s[/tex]

substituting values

     [tex]D = 4.484+ 23.28[/tex]

     [tex]D = 27.76 \ m[/tex]