Not So Simple
Figure 1. The bicycle, a compound machines.Copyright Queen's Printer for Ontario, 2007, Archives of Ontario, http://www.archives.gov.on.ca/english/common/c510681.htm
Students expand upon their understanding of simple machines with an introduction to compound machines. A compound machine — a combination of two or more simple machines — can affect work more than its individual components. Engineers who design compound machines aim to benefit society by making work easier for people, even common household tasks. This lesson encourages students to critically think about machine inventions and their role in our lives.
Inventing and designing are at the heart of engineering. Engineers use their math and science knowledge to create new products or improve existing ones in hopes of improving people's lives. There is a certain process engineers go through when they invent or design a new or improved product called the engineering design process. This process includes identifying the needs and constraints, researching the problem, thinking of possible solutions, selecting the most promising solution, modeling/testing the system or process, then iterating and improving the product until the optimal solution within the given constraints is achieved. Much of mechanical design involves the simple and compound machines described in this unit.
After this lesson, students should be able to:
- Recognize how compound machines are used in many familiar engineering systems today and name several found in daily life.
- Explain the difference between compound and simple machines.
- Explain how to calculate the mechanical advantage of compound machines.