Final answer:
Simple machines do not decrease the total work performed as they abide by the conservation of energy principle; they alter the force required and the distance over which the force is applied and provide mechanical advantage.
Step-by-step explanation:
We would not expect the work performed by each simple machine to be exactly the same as the work performed without it. The reason for this is based on the conservation of energy principle in physics, which states that in closed systems the total amount of energy is conserved. While a machine cannot increase the total amount of energy put into it, simple machines are beneficial because they can change the amount of force required and the distance over which the force is applied. Essentially, they reduce the input force needed, but increase the distance over which this force must be exerted, keeping the product of force and distance constant, as this product represents work.
The usefulness of a simple machine lies in its capacity to provide mechanical advantage (MA), which is the ratio of output to input force magnitudes. For example, a lever may require less force to lift a weight but will require that force to be applied over a longer distance. A simple machine simplifies tasks by allowing efficiency in energy transfer, but the total work done remains the same because work is a product of the force applied and the distance over which it is applied.