Introduction
Not only does it take a lot of force and quite a bit of time (and therefore distance) to accelerate big vehicles like trains, but it also takes a lot of force and time and distance to stop them. Imagine the force required to slow down and stop a train weighing 20,000 tons that's traveling at 80mph, when the engineer sees that there is an automobile stuck on the tracks ahead! Exactly how much force would that take? How much stopping time would be required, and how much stopping distance? That's what this lesson is about.
As you might imagine, there are many factors involved in calculating the stopping distance required for such a massive vehicle. This lesson teaches the basic ideas.
Figure 3.3.1. It takes a lot of force, time, and distance to get trains up to speed--and also to stop them.