Although these simple machines have been known and used for thousands of years, no other simple machines have been discovered. Two other common simple machines, the screw and the wedge, are really adaptations of the inclined plane. Work Print section Machines help people do work by changing the amount of force and the distance needed to move objects. Work, in physics, is the amount of force used to move an object multiplied by the distance over which the force is applied. Force Distance Force is defined as a push or a pull exerted on one body by another, such as a hand pushing a book across a table.
Distance refers to the distance a load is moved by the force.
Knowing the mechanical advantage of a machine allows a user to predict how much force is needed to lift a given object. A machine can make a given task seem easier by reducing the amount of force needed to move an object, by changing the direction in which the force must be applied, or by doing both. A machine decreases the amount of force needed by increasing the distance over which the effort is applied to move the object. The amount of work needed to overcome gravity and lift a given load always remains the same, but spreading the necessary effort out over a longer distance makes the task seem easier. This is why walking gradually up a gentle slope is easier than walking up a steep slope.