the car has kinetic energy ... 1/2 m v^2
to stop the car; the work done by the brakes (f * d) must equal the car's kinetic energy
(a) 1/2 * 1.00E3 * 35.0^2 = 8.00E3 * d
(b) find the work done in 30.0 m and subtract it from the initial K.E.
... the remaining energy will give the collision speed
The driver of a 1.00X103 kg car traveling on the interstate at 35.0 m/s slams on his brakes to avoid hitting a second vehicle in front of him, which had come to rest because of congestion ahead. After the brakes are applied, a constant friction force of 8.00X103 N acts on the car. Ignore air resistance.
(a) At what minimum distance should the brakes be applied to avoid a collision with the other vehicle?
(b) If the distance between the vehicles is initially only 30.0 m, at what speed would the collision occur?
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