1. A railroad diesel engine weighs four times as much as a freight car. If the diesel engine coasts at 5 km/h into a freight car that is initially at rest, show that the two coast at 4 km/h after they...

1. A railroad diesel engine weighs four times as much as a freight car. If the diesel engine coasts at 5 km/h into a freight car that is initially at rest, show that the two coast at 4 km/h after they couple together.

2. A 5-kg fish swimming at 1 m/s swallows an absentminded 1-kg fish at rest. (a) Show that the speed of the larger fish after lunch is –5 m/s. (b) What would the speed of the larger fish be if the smaller fish were swimming toward it at 4 m/s?