Three identical train cars, coupled together, are rolling east at 2.0 m/s. A fourth car traveling east at 4.0 m/s catches up with the three and couples to make a four-car train. A moment later, the train cars hit a fifth car that was at rest on the tracks, and it couples to make a five-car train. What is the speed of the five-car train?

Solution 34 P

Step 1 of 3</p>

We are required to calculate the speed of the five-car train

Step 2 of 3</p>

Case 1

Consider the mass of each car , kg

Three car’s moving together with velocity m/s and kg

The fourth car velocity is m/s

According to conservation of linear momentum for the system of three cars and fourth car

m/s