Students can construct a small pulley elevator in an old dresser drawer. Insert three large screw-in hooks in one of the drawer's short side panels. Tie a length of masonry twine tightly around the hook on the left side of the drawer and suspend a pulley from the other two hooks. Leaving plenty of slack from the first hook, wrap the twine over both pulleys. Place a third pulley on the twine so it threads under to provide an opposing force between the twine's point of origin at the hook and the other pulleys. Suspend a platform under the third pulley by running string from each platform corner and connecting on the pulley's lower hook. Pull and release the loose end of the twine to raise and lower the platform with loads of various sizes.
Rural homes in developing countries are often built on stilts to prevent flooding or provide shade to farm animals. Disabled individuals living in these areas may find it difficult to enter and exit their houses without the assistance of pulleys. Students should build a model stilt house from cardboard and scrap lumber to model a personal transport pulley system. Mount a sturdy ridge pole that extends from the house about 6 inches and mount a single-hook pulley on the pole. Tie a length of string around a house stilt and wrap over the pulley. Set another single-hook pulley on the string and loop the string back up over the first pulley and down to the ground. Create a canvas sling held together at two corners with string and hang the center of the string on the hook of the lower pulley. Place a doll in the sling and demonstrate how a person with strong arms could raise or lower the lift by pulling hand over fist up the string to reach the elevated level and controlling the release of string down to the ground.
High school students will demonstrate principles of force, weight distribution and work to determine the most efficient pulley system for raising a load. Construct two models of the traditional fixed block and tackle and belt and pulley systems, employing small pulleys in one model and large pulleys in the other. Attach equal-sized weights to each one and lift each one. Measure the amount of work required to raise each load with a spring scale. Conclude whether the size or number of pulleys in a system affects the amount of effort required to achieve the work. Test another variable by repeating the experiment with movable pulleys instead of fixed systems.
For a truly impressive science project, advanced physics students should research pulley systems extensively and determine a design that will allow a single person to lift the weight of an entire class. Obtain school permission to build the pulley in a classroom or other large area, such as the gym or cafeteria. Put mathematical calculations to the ultimate test by inviting everyone in your science class to climb on the platform and ask the teacher to raise it using your pulley system design.