Careful When You Hit the Tracks

A new train engineer was learning about his duties and his assigned route.

“first,” he was told, ” there’s a long slope down.  You can coast, gathering speed.”

“Next,” he was told, “there is a long flat stretch.  You can coast for a while on the speed from the slope and then you will continue to chug along under your own power.”

“Sounds easy,” the fresh-faced engineer said, ” so what’s the problem?”

“The problem is the switch.  When you come barreling down the slope and are abruptly pulled up by the flats.”