Trains approaching constant acceleraton problem

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Homework Help Overview

The problem involves two trains approaching each other with constant acceleration from rest, initially 40 meters apart. The left train accelerates at 1.12 m/s² to the right, while the right train accelerates at 1 m/s² to the left. The objective is to determine how far the left train travels before the trains' front ends pass each other.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relative displacement between the two trains and question how to determine the time it takes for them to meet. There are suggestions to write out the motion equations for each train and to consider relative motion.

Discussion Status

The discussion is ongoing, with participants exploring different approaches to the problem. Some have attempted calculations related to time and distance, while others are seeking clarification on how to set up the equations of motion.

Contextual Notes

Participants are working under the constraints of the problem's parameters, including the initial conditions and accelerations of the trains. There is a focus on understanding the relationships between the trains' motions rather than arriving at a final solution.

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Homework Statement


Two trains face each other on adjacent tracks. They are initially at rest, and their front ends are 40m apart. The train on the left accelerates rightward at 1.12m/s2. The train on the right accelerates leftward at 1 m/s2. How far does the train on the left travel before the front ends of the trains pass?

The Attempt at a Solution


I found that it takes the left train 9.258s to travel 48m. It takes the right train 9.798s to travel 48m as well. This is useless info I think. I also found their final velocities.

But I also think that is useless info. I need some help on how to do this problem.

Thanks!
 
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What is the relative displacement between the two front ends? Or, in other words, how far apart are the two front ends at every point in time?

What is \vec x_{12}?
Find how long it takes for them to 'meet' and then look at how much the one train has traveled over that time.

\vec x_{12}\equiv \vec x_1-\vec x_2
 
How do I find how long it takes them to meet?
 
Write out the motion equations for each of the trains and then use relative motion to find how long it takes for them to meet.

Find:
\vec x_1(t) and \vec x_2(t)
 

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