>13. In this the lower pulley is movable. One end of the rope being fixed, the other must move twice as fast as the weight, and a corresponding gain of power is consequently effected.

Why is lifting a weight attached to a movable pulley more efficient than simply lifting the weight over a fixed pulley? Also, what does it mean for one end of the rope to move at twice the speed as the weight, surely they have to move at the same speed to stay connected? Please explain for a very smol brain