Question

The driver of a 1000 kg car traveling on the interstate at 35 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 800 N acts on the car. Ignore air resistance, at what minimum distance should the brakes be applied to avoid collision with the other vehicle

Answer 1

765.625 m

Step-by-step explanation:

When brakes are applied , work is done by frictional force to reduce the kinetic energy of the car . To stop the car , the work done by brake must equalize the kinetic energy of car .

1/2 m v² = F d

m is mass of the car , v its velocity , F is frictional force and d is displacement of car .

1/2 x 1000 x 35² = 800 x d

d = 765.625 m