Final answer:
Roads and highways are most slippery when there is a lack of friction. Friction is desirable in situations where traction or grip is needed.
Step-by-step explanation:
Roads and highways are most slippery when there is a lack of friction between the tires and the road surface. This occurs when the road surface is wet or icy, which reduces the grip of the tires. When the roads are slippery, it is important for drivers to take precautions such as reducing their speed and increasing the distance between vehicles to avoid accidents.
Friction is desirable in situations where we need traction or grip. For example, in sports like soccer or basketball, players wear shoes with rubber soles that provide high friction on the court, allowing them to change directions quickly and prevent slipping. Similarly, in rock climbing, climbers use shoes with sticky rubber soles that maximize friction, helping them grip onto rocks securely.