Four people were in a car whose brakes failed going down a steep hill.

     The driver was skilled enough to steer the car away from obstacles while it rolled to a stop and suggested having it towed to repair shop.

     The physicist wanted to do the mass-velocity calculation to figure out how much potential and kinetic energy was involved in the slowdown.

     The engineer wanted to do an analysis of the braking system of the car to figure out what might have gone wrong.

     And the computer scientist suggested pushing the car back up the hill, turning it off, restarting it, and seeing if the problem recurs.