The Power of Mechanical Advantage
Students explore the mechanical advantage of pulleysCopyright 2010 Polytechnic Institute of NYU
Students learn about the mechanical advantage offered by pulleys in an interactive and game-like manner. By virtue of the activity's mechatronic presentation, they learn to study a mechanical system not as a static image, but rather as a dynamic system that is under their control. Using a LEGO® MINDSTORMS® robotics platform and common hardware items, students build a mechanized elevator system. The ability to control different parameters (such as motor power, testing load and pulley arrangement) enables the teacher, as well as the students, to emphasize and reinforce particular aspects/effects of mechanical advantage.
The mechanical advantage offered by pulleys is probably the most self-evident example of simple machines used pervasively in industry and everyday life. Pulleys, in their various configurations, are often seen in engineered cranes, elevators, boats and construction hoists. Although knowledge of simple machines is often conveyed in the form of diagrams on blackboards or on paper, pulleys are in fact not as static as they are presented in such one-dimensional drawings. Witnessing the mechanical advantage offered by pulleys benefits from movement, as this activity demonstrates.
After this activity, students should be able to:
- Clearly and confidently explain that pulleys are simple machines that offer mechanical advantage and define mechanical advantage in the form of examples.
- Draw diagrams of pulley set-ups that are capable of applying mechanical advantage.
- Predict observations of a system's lifting abilities if pulleys are added to it (that is, the ability to lift objects that the motors were previously unable to lift, and the loosening of tension amongst load line segments).