It is easier to lift the same load by using three-pulley system than by using two-pulley system.
Answers
In the two pulley system, the weight is divided between the two points only.
Since the weight is high on the end it will make the friction to increase that will be difficult to lift the weight.
In the three pulley system, the weight will be divided into three different parts that will divide the friction making it easy to pull.
answer
In determining the force required to do work it is dependent on the number of ropes supporting the load. This Is the only way of calculating the force required to lift the load.
Some pulleys can have multiple sheaves which affects the number of ropes supporting the load versus a single sheave pulley.
Or
In the two pulley system, the weight is divided between the two points only. .
.. In the three pulley system, the weight will be divided into three different parts that will divide the friction making it easy to pull .