Final answer:
The coefficient of dynamic friction between the tire and the ground, under the given conditions with a velocity of 20 m/s and a displacement of 50 m, and with the acceleration due to gravity at 10 m/s², is found to be 0.4.
Step-by-step explanation:
To find the coefficient of dynamic friction between the tire and the ground, we need to use the concept of work and energy. When the car moves on a rough horizontal road and comes to a stop, the work done by friction is equal to the change in kinetic energy. The initial kinetic energy of the car can be calculated using the formula ½mv2, where 'm' is the mass of the car, and 'v' is the initial velocity. However, since the mass of the car is not given, it will cancel out in the subsequent calculation.