If anyone could explain how to solve this problem, I would greatly appreciate it.
A railroad diesel engine weighs four times as much as a freight car. If the diesel engine travelling at 5 km/h hits a freight car that is initially at rest, how fast do they both move after they have coupled together?
Thanks!
A railroad diesel engine weighs four times as much as a freight car. If the diesel engine travelling at 5 km/h hits a freight car that is initially at rest, how fast do they both move after they have coupled together?
Thanks!
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Conservation of Momentum applies.
Let the mass of the freight car be M kg.
Hence the mass of the engine = 4M kg
Momentum of the engine on its own = 5 * 4M
= 20M kg.km/h
Momentum of the two together
= 20M (momentum is conserved)
but the mass is now 5M
Speed * Mass = 20M
Speed = 20m / 5M = 4 km/h
Let the mass of the freight car be M kg.
Hence the mass of the engine = 4M kg
Momentum of the engine on its own = 5 * 4M
= 20M kg.km/h
Momentum of the two together
= 20M (momentum is conserved)
but the mass is now 5M
Speed * Mass = 20M
Speed = 20m / 5M = 4 km/h