Calculate final velocity

  • #1

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 traveling at 45 km/h [N].
Engine 2 has a mass of 1.5x10^4 kg and is initially traveling 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

The answer in the textbook is 9.7m/s. What am I doing wrong?
  • #2
I just realized my mistake, i forgot to divide it by both mass

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