Acar is being driven along a country road on a dark and rainy night at a speed of 20 m/s. the section of road is horizontal and straight. the driver sees that a tree has fallen and covered the road ahead. panicking, the driver locks the brakes at a distance of 20 m from the tree. if the coefficient of friction between the wheels and road is 0.8, determine the outcome.

Car collides.

Explanation:

The (negative) acceleration experimented by the car will be given by Newton's 2nd Law , where f is the friction force, which is the only force acting on the car on the horizontal direction. Its value is given by the formula since the normal force and the weight of the car are balanced on the vertical direction. All this gives us the equation

To calculate the distance traveled by the car, we will use the equation for accelerated motion on the form (since it comes to a rest ):

Which for our values is (taking the direction of movement as positive, which makes a negative, so we add a -1 to account for this):

Which means the car crashes against the tree.

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