The drawing below shows two different types of pulley systems designed to lift a weight. In pulley system A, the end of the rope
must be pulled 10 cm downward in order to raise the weight 10 cm upward. In pulley system B, the end of the rope must be pulled 20 cm downward in order to raise the weight 10 cm upward. What is the mechanical advantage for each pulley system?
Assuming the weight is the same in both cases and in the first system there is only 1 pulley, then in the second case must be 2 pulleys, because the end of the rope is pulled double than before.
In the second case, therefore, the force applied is half than the first case, and that´s the mechanical advantage of a multiple wheel pulley. In the 2 pulleys system, the mass is supported by two sections of the same rope instead of just one and this means you can lift the mass by pulling with a force which is half of the mass weight.
