Final answer:
Stopping distance includes reaction distance and braking distance, both of which are critical for road safety and necessary for determining safe following distances and when it's safe to cross in front of a moving vehicle.
Step-by-step explanation:
The question relates to the stopping distance of a vehicle, which is a key concept in Physics and important for road safety. Stopping distance is typically divided into two components: the reaction distance and the braking distance. Reaction distance is the distance your vehicle travels from the moment you first perceive a hazard until you react by stepping on the brake. This distance depends on the reaction time and the speed of the vehicle.
For example, at a speed of 50 mph (approximately 22.35 m/s), if it takes 1.5 seconds for a driver to react, the reaction distance would be:
Reaction Time (s) x Speed (m/s) = Reaction Distance (m)
1.5 s x 22.35 m/s = 33.53 m
After reacting, the next component is the braking distance, which is the distance your vehicle travels from the time you apply the brakes until it comes to a complete stop. This depends on factors such as speed, vehicle mass, brake condition, road condition, and coefficient of friction between tires and road.
Braking distance can be tested by driving a car at 50 mph and applying the brakes until the vehicle stops. You record the distance taken to stop, which, along with the reaction distance, gives you the total stopping distance. This is critical for determining safe following distances and crossing times as it gives you an understanding of the minimum distance needed to avoid a collision.
When a vehicle is moving towards you at a given speed, to decide if it's safe to cross, you need to estimate its stopping distance and compare that to the distance between you and the vehicle. Therefore, a car that is 28 m away and has a stopping distance greater than 28 m would not be considered safe to cross in front of without the risk of a collision.