Final answer:
When roads are wet, the three-second rule should be increased to at least four seconds to help ensure safety under the more hazardous conditions. The increase in the following distance accounts for longer stopping distances on wet roads.
Step-by-step explanation:
When roads are wet, it is typically recommended to increase the three-second rule to four or more seconds. This longer following distance provides additional safety margin for stopping in slippery conditions.
The three-second rule is a guideline that suggests a driver should stay at least three seconds behind any vehicle that is directly in front of the driver's vehicle. This time gap allows for adequate space for the driver to respond to potential sudden stops of the vehicle ahead. However, on wet roads, factors such as decreased tire traction and longer stopping distances significantly affect braking capability. Therefore, the rule of thumb is to extend this safe following distance.
Assuming a car is traveling at 30.0 m/s and the driver has a reaction time of 0.500 seconds, the vehicle will travel an additional 15.0 meters before the driver begins to brake. On wet pavement, the combined distance of reaction and braking is more significant than on dry pavement, hence the need for a longer following distance. This example emphasizes the significance of adjusting driving practices according to road conditions for safety.