When you use a jack to lift a car, the force you exert on the jack is much less than the weight of the car. Does this mean that less work is done on the car than if the car were lifted directly?
The work done in both cases is the same and will be equal to the change in potential energy the car has gained by being lifted. Work = Force x Distance If you lift the car directly you will apply a LARGE force over a SHORT distance. I you lift the car with a jack, you will be applying a Small force over a LONG distance (distance being the product of how many times you pump the handle and the travel distance each time) Bottom line. Force x Distance is the same ... and so is the work.
