Mechanical advantage force applied at "A" the end of the rope, and let "F" be the force at "B" on the moving block. Like the velocities "F" is directed downwards and "F" is directed upwards. For an ideal block and tackle system there is no friction in the pulleys and no deflection or wear in the rope, which means the power input by the applied force "F""V" must equal the power out acting on the load "F""V", that is The ratio of the output force to the input force is the mechanical advantage of an ideal gun tackle system, This analysis generalizes
Block and tackle each of the parts of the rope must be "F/n." This means the input force on the rope is "F"="F/n." Thus, the block and tackle reduces the input force by the factor "n." Ideal mechanical advantage correlates directly with velocity ratio. The velocity ratio of a tackle is the ratio between the velocity of the hauling line to that of the hauled load. A line with a mechanical advantage of 4 has a velocity ratio of 4:1. In other words, to raise a load at 1 metre per second, the hauling part of the rope must be pulled at 4