Question

The driver of a 1,000 kg car travelling at a speed of 16.7 m/s applies the car's brakes when he sees a red light. the car's brakes provide a frictional force of 8,000 n. determine the stopping distance of the car.

Answer 1

Energy conservation : 
kinetic energy Ek = braking work W 
mV^2 = 2Fb*x 
x = mV^2/2Fb = 1000*16.7^2/16.000 = 17.43 meters

Answer 2

Answer:

1.04 meters

Explanation:

Thinking process:

Gathering the data

mass  = 1 000 kg

speed, u = 16.7 m/s

Frictional force = 8 000 N

distance, s  = ?

final velocity  = 0 (car stops)

We know that the final velocity is calculated as: $v^{2} = u^{2} + 2as$

But, a = negative (declaration)

And F = ma

      $8 000 = 1000 (a)\\ a = -8 m^{-2}$

substituting, 0 = (16.7) - 2 (8) (s)

                    -16.7 = -16s

                         s  = 1.04 m

   Stopping distance = 1.04 meters