Final answer:
To ensure pedestrian safety, a vehicle should stop at a safe distance from a crosswalk, taking into account speed, road conditions, and driver reaction time. Typically, stopping within the distance of several car-lengths is considered safe. When crossing, a pedestrian should consider the speed and distance of oncoming traffic, with 28 m (8 car-lengths) being a potential reference point for safety.
Step-by-step explanation:
When considering pedestrian safety and assessing the safe distance to stop a vehicle at a crosswalk, several factors are important. The stopping distance will vary greatly depending on road conditions and the driver's reaction time. For example, if a car is initially traveling at 30.0 m/s on dry pavement and the driver reacts to a red light, there is a calculated braking distance plus the distance covered during the driver's reaction time. It is contextual how many feet specifically, as it depends on the speed limit and the conditions, but generally, a safe rule could be to stop the vehicle within the distance of several car-lengths from a crosswalk to ensure safety.
In a situation where a pedestrian is trying to determine if it is safe to cross the road, if a car is observed to be 28 m away, which is approximately equivalent to the length of 8 average cars, one must consider the speed of the oncoming vehicle. If this distance allows enough time for the pedestrian to cross with a safe margin, considering the speed and reaction time of the driver, only then would it be considered safe to cross.