Thursday, April 10, 2008

Physics 101

This afternoon an elderly, white haired passenger stopped me and asked a question.

"Conductor, what do you call the guy who drives the train? Is he a motorman?"

"No," I said. "On the subway they're called motorman. Here they're called engineers."

"Okay then, my colleague and I have a question about the engineer."

I thought I was going to hear a complaint about where the engineer had spotted the train on the platform, and I was mentally preparing an answer.

"I know it's kind of an oddball question," he said, "but we're wondering...Is it harder for the engineer to accelerate when the train is packed full of passengers?"

"Hmm," I said. "That's an interesting question. I'd have to say no."

I tried to look learned and knowledgeable as I expounded on my theory. "You see, these trains are extremely heavy," (I had no idea what I was talking about, but I wasn't going to let that stop me) "and the added passenger weight is negligible to the train's performance."

My passengers looked pretty impressed with my explanation and they thanked me for my time and expertise.

I knew I'd shoveled the BS pretty deep, and feeling guilty, I walked up to the head car and knocked on the engineer's cab door. "Hey Mark," I said, "a passenger just asked if it's harder for you to accelerate when the train is full versus when it's empty."

"A crowded train is much more sluggish," he said.

"Yeah," I said. "That's what I thought."

I then swallowed my pride, walked back to my inquisitive passengers, and told them what the engineer had said.

"Yeah," they said. "That's what we thought. It's basic physics."


El Cobrador said...

This has been a topic of discussion out here in Amtrak California territory. What type of train do you work? Is it diesel-hauled, electric-hauled, MU, or some other type? We run four or five-car, bi-level trains with 3000-4000 horsepower locomotives. Engineers that I've discussed this with have indication that they've noticed no difference in performance with a packed train. Our equipment seems to me to be extremely heavy already. I'm no physics major, however

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eric said...

el cobrador: That would fly in the face of E=mc2. Even dead mass, or passengers, creates energy. Chances are you are just dealing with engines that overpower it to the point that it's not an issue. It's kind of a cool Mythbusters question to show that the idea of mass and speed equaling energy just cannot be gotten around, no matter how it feels.