(adsbygoogle = window.adsbygoogle || []).push({}); 1. Why is the following situation impossible? A freight train is lumbering along at a constant speed of 16.0 m/s. Behind the freight train on the same track is a passenger train traveling in the same direction at 40.0 m/s. When the front of the passenger train is 58.5 m from the back of the freight train, the engineer on the passenger train recognizes the danger and hits the brakes of his train, causing the train to move with acceleration -3.00 m/s2. Because of the engineer’s action, the trains do not collide.

I first calculated the distance it takes passenger train to stop:

0 = (40)^{2}-2(3)[itex]\Delta[/itex]x

Solving, [itex]\Delta[/itex]x = 266.7 m to stop

Next I calculated the time it took to stop:

0 = 40 - 3(t), solving, t = 13.3 s

Next I calculated the distance of the freight train in those 13.3 seconds,

distance = 13.3 * 16 m/s = 213.3 m

Since the separation is 58.8 m before the passenger train braked, and the freight train goes 213.3 before the passenger train stops, I added 58.8 + 213.3 = 271.8 m

271.8 > 266.7, thus it appears the passenger train WILL stop just in time, but the problem obviously doesn't think so... what did I do wrong?

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# Homework Help: Why is the following impossible? 2 trains

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