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## Homework Statement

Two freight trains have a completely inelastic collision at a track crossing. Engine 1 has a mass of 1.4x10^4 kg and is initially travelling at 45 km/h [N].

Engine 2 has a mass of 1.5x10^4 kg and is initially travelling at 53 km/h [W]. Calculate the final velocity.

## Homework Equations

## The Attempt at a Solution

p^2=p1^2+ p2^2

=(1.4x10^4)(12.5m/s)^2+ (1.5x10^4)(14.72m/s)^2

=281740m/s

The answer in the textbook is 9.7m/s. What am I doing wrong?