Calculate the effort needed to lift a load using a pulley system with mechanical advantage.
Each real pulley has friction losses, typically 3-5% per pulley. With 4 pulleys at 95% efficiency, actual MA ≈ 3.25 instead of the ideal 4. More pulleys help but with diminishing returns due to accumulated friction.
Fixed pulleys change force direction only. Movable pulleys provide 2:1 MA. A block and tackle combines both for higher MA. Compound pulleys can achieve 4:1 or higher ratios for heavy lifting.