Which of the following increases efficiency in a machine?

Efficiency in a machine is typically defined as the ratio of useful output work to total input work. When it comes to improving this efficiency, reducing the effort required to perform the same task is crucial.

Reduced effort allows the machine to operate with less energy input while maintaining the same level of performance. This can lead to less wasted energy, as the machine requires less force to achieve the desired motion or outcome. In essence, when a machine performs more effectively with less input — which is indicated by reduced effort — it means that the work done is maximized relative to the energy consumed.

In contrast, increased friction creates losses in the system, as more energy is wasted overcoming frictional forces. Decreased motion suggests less activity without specifying the effectiveness, while longer load arms could increase the distance over which a load is moved, but may not necessarily lead to a gain in overall machine efficiency unless they are appropriately used in conjunction with a reduction in effort or friction. Thus, reducing the required effort is a direct way to enhance the machine's efficiency.