A railroad diesel engine weighs four times as much as a freight car. If the diesel engine coasts at 4 km/h into a freight car that is at rest, how fast do the two coast after they couple (in km/h)?
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Momentum before=momentum after
mv+mv=mv+mv
4*4=(4+1)*v
16=5v
v=16/5 km/h
mv+mv=mv+mv
4*4=(4+1)*v
16=5v
v=16/5 km/h