What is it about the movable pulley that causes the difference in force?
Answer (2)
There is normally friction across the pulley. If a weight is suspended by a rope, and the rope goes across a pulley, the pulley exerts friction on the rope if there is any movement, giving rise to inaccuracies in calculations.
A movable pulley reduces the force needed to lift an object by providing a mechanical advantage based on the number of rope sections supporting the load. When friction is minimized, the force you need to apply can be significantly less than the load itself. Understanding this principle allows for effective use of pulleys in various applications.
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