Final answer:
You must maintain a safe following distance when driving behind a semi-truck, which is typically a minimum of 4 seconds. Stopping distances depend on speed, deceleration, and reaction time, and can be crucial to safety. For every 10 mph of speed, it is advised to leave one car length of space in ideal conditions.
Step-by-step explanation:
The question pertains to the safe following distance when driving behind a semi-truck. Although the exact space may vary depending on driving conditions and speeds, a general rule of thumb is to maintain a minimum following distance of 4 seconds or more. This rule ensures you have enough time to react if the semi-truck were to stop suddenly or if any other unforeseen events occur on the road.
In scenarios where a truck is traveling at a constant velocity and must come to a sudden stop because a child is in the road, the distance needed to stop will depend on the truck's initial speed, the deceleration rate, and the reaction time of the driver. Given the specifics, like a deceleration rate of -1.25 m/s² and a reaction time of 0.5 seconds, the total stopping distance can be calculated and compared to the child's distance to determine if the truck will stop in time.
It is crucial for safety to maintain an adequate following distance from all vehicles, not just semi-trucks. Common safety advice suggests that for each 10 mph of speed, drivers should leave one car length of space in ideal conditions, and more during poor conditions. Understanding stopping distances, like those detailed in the physics scenario provided, helps inform safe following distances in real-world driving.