WHAT DO YOU MEAN BY WORK ?

Suppose the engine of your car stalled while you were in line to exit from a flat, level parking lot. You try several times to restart it, but it just won't start.

Since you are a considerate person, you decide to push your car out of the way of the people behind you. You get out and go round back and begin to push on the car

. Suppose also that you are a fairly strong person, so you exert a horizontal force of 100 pounds on the rear of the car. The car doesn’t move. But you are also a persistent person, so you continue to push on the car for two whole minutes, exerting the same 100 pounds of force. The car still won’t move. Although you will probably be quite tired, you will have done NO WORK.

WHY? Because WORK is defined as a FORCE operating through a DISTANCE. The car didn’t move, so although there was FORCE, there was no MOTION.

Now you get smart and release the parking brake, and, having recovered from your previous 2-minute exercise in futility, you again push the car with the same constant 100 pound force. This time the car moves, and you push it for another two minutes. It travels 165 feet during that two minutes of effort. In that case, you will have produced 16,500 foot-pounds of  WORK (100 pounds of force x 165 feet of distance = 16,500 foot-pounds).