Pulley If there are "p" of these parts of the rope supporting the load "W," then a force balance on the moving block shows that the tension in each of the parts of the rope must be "W/p." This means the input force on the rope is "T"="W/p." Thus, the block and tackle reduces the input force by the factor "p." The simplest theory of operation for a pulley system assumes that the pulleys and lines are weightless, and that there is no energy loss due to friction. It is also assumed that the lines do not stretch. In equilibrium, the
Ant on a rubber rope Ant on a rubber rope The ant on a rubber rope is a mathematical puzzle with a solution that appears counterintuitive or paradoxical. It is sometimes given as a worm, or inchworm, on a rubber or elastic band, but the principles of the puzzle remain the same. The details of the puzzle can vary, but a typical form is as follows: At first consideration it seems that the ant will never reach the end of the rope, but in fact it does. (In the form stated above, it would take 8.9 years.) Whatever the length of the rope and the