Final answer:
The three-second rule is designed to help drivers maintain a safe following distance by ensuring there is enough space between cars for safe stopping under normal driving conditions. It accounts for driver's reaction time and the vehicle's braking distance.
Step-by-step explanation:
The purpose of the three-second rule is to maintain a safe following distance under normal driving conditions. This rule helps drivers to gauge if they are too close to the car in front of them. To utilize this rule, a driver watches as the car ahead passes a stationary object, like a pole or tree, and then counts off three seconds (ideally using 'one thousand one, one thousand two, one thousand three'). If the driver passes the same stationary object before reaching three seconds, they are too close and need to increase their following distance.
This rule ensures there's sufficient space to stop safely without a collision, taking into account the reaction time of the driver, the distance covered during this reaction time, and the braking distance once the brakes are applied. These components together constitute the total stopping distance. In inclement weather or poor road conditions, the following distance should be increased, as both reaction time and braking distances can be affected, leading to a longer total stopping distance.
To be more precise, figuring out the stopping distance involves understanding how long it takes for the driver to react and hit the brakes, plus the vehicle's stopping distance after braking begins. Therefore, Bridget's observation from her classroom about cars taking 3 seconds to travel between two poles is related to the speed of the car but is not directly related to the three-second rule for following distance.