Train A, \(m_{\mathrm{A}}=150,000 \mathrm{~kg}\), is traveling west at \(60 \mathrm{~km} / \mathrm{h}\). Train B, \(m_{\mathrm{B}}=100,000 \mathrm{~kg}\), behind train A on the same track, is traveling west at \(88 \mathrm{~km} / \mathrm{h}\) and so is gaining on train A. Because the engineer driving B fails to slow down, \(B\) runs into the back of \(A\). The two trains stick together and then move as a single unit after the collision. What is the momentum of each train before the collision and after the collision according to \((a)\) an observer standing alongside the tracks and \((b)\) an observer in a westbound automobile traveling at \(100 \mathrm{~km} / \mathrm{h}\) on a road that parallels the tracks?