Final answer:
It is difficult to stop or accelerate a car on ice due to the low friction between the tires and the ground. Friction is essential for vehicles to move and stop effectively. On an icy surface with nearly zero friction, an object's acceleration becomes zero once the applied force stops, but it keeps moving at a constant speed.
Step-by-step explanation:
The difficulties in stopping and accelerating a car on an icy road are due to there being little to no friction between the tires and the ground. Friction is a force that occurs between two surfaces in contact, acting opposite to the direction of motion or intended motion, and is necessary for vehicles to accelerate and decelerate effectively. Without sufficient friction, as is the case on ice, tires cannot grip the road to push against when accelerating, and similarly, they cannot create the necessary resistance to slow down when braking.
Another example where more friction is desirable is when playing sports like basketball, where players need good traction on the court to stop, start, and change direction quickly.
When a force is applied to accelerate an object on a smooth icy surface with zero friction, and then the force stops, the object's acceleration becomes zero, but it would continue to move at a constant velocity due to inertia, as described by Newton's first law of motion.