How does a lever help in reducing the work done to lift an object.
It is a common misconception that a lever helps in reducing the work required to lift an object. The work required to lift an object when a lever is used is same as that required to lift the object without the lever.
A lever helps by reducing the magnitude of the force that has to be applied. A lever has three components, a load arm, a force arm and the fulcrum. The load is placed at the end of the load arm and the force is applied at the end of the force arm. If the length of the load arm is Ll and that of the force arm is Lf, to lift the load we need to apply a force equal to Ll/Lf. If the load arm is shorter than the force arm there is a reduction in the force that has to be applied. But to accomplish this the force applied at the end of the force arm has to be moved a much larger distance that is Lf/Ll that of the distance by which the load moves. This makes the total work done equal.
The only way in which a lever helps is by reducing the force that has to be applied. It is easier to move a small force by a large distance rather than move a large force by a small distance.