- #1

lordZeR0

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**1. Problem Statement**

Two trains face each other, adjacent tracks.

Both at rest, and front ends are 40m apart.

Left train accelerates at 1.0m/s^2.

Right train accelerates at 1.3m/s^2.

A) How far does train on the left travel before the front ends of the trains pass?

B) If trains are each 150m in length, how long after the start are they completely past one another, assuming their accelerations are constant?

## Homework Equations

x = v*t+.5*a*t^2

vf = vi+a(t)

x = vi*t+.5a*t^2

A drawing:

http://www11.picfront.org/token/y4KU/2010/02/01/1751429.jpg [Broken]

**3. Attempt to reach answer.**

A)Will this approach work? To solve , we want to get xA = xB , A and B trains on each side, and x = distance.

so setting (vi*t+.5a*t^2)A = (vi*t+.5a*t^2)B

What i did was use:

x = v*t+1/2*a*t^2

40m = 0 + .5*1.0*t^2

Solve for t, t= sqrt(80/1) => 8.95seconds

Next use vf = vi+a(t)

vf = 0+a(t)

vf = 0 + (1.0)(8.95) => 8.95m/s

Vice versa for b train, vf = 10.20m/s , t = 7.85 seconds

With v obtained, I have no idea what to do? A tip?

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