Pulley'ing Your Own Weight
Using common materials (spools, string, soap), students learn how a pulley can be used to easily change the direction of a force, making the moving of large objects easier. They see the difference between fixed and movable pulleys, and the mechanical advantage gained with multiple/combined pulleys. They also learn the many ways engineers use pulleys for everyday purposes.
Figure 1. Pulleys help build everything. Engineers use pulleys to construct buildings like the Supreme Court Building.Copyright U.S. Supreme Court, http://www.supremecourtus.gov.
Thousands of years ago as well as today, engineers used pulleys to make everyday tasks and large construction projects easier. They use pulleys to raise heavy objects, taking advantage of gravity to help lift an object. Engineers incorporate pulleys into a wide range of modern-day applications, such as cranes for lifting very heavy objects in construction projects, elevators, flagpoles, motors, bicycles and boats. To gain a mechanical advantage using multiple pulleys in conjunction with motors and electronics, engineers create devices that operate with very little power for how much work they perform.
After this activity, students should be able to:
- Describe how pulleys make work easier for engineers.
- Demonstrate the difference between fixed and movable pulleys.
- Describe everyday examples of pulleys used by engineers.