1. Hands-on Activity: Machines and Tools, Part II Contributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado at Boulder

2. Summary In this activity, students gain first-hand experience with the mechanical advantage of pulleys. Students are given the challenge of helping save a whale by moving it from an aquarium back to its natural habitat into the ocean. They set up different pulley systems, compare the theoretical and actual mechanical advantage of each and discuss their recommendations as a class.

3. Learning Objectives After this activity, students should be able to: Calculate the mechanical advantage of a pulley. Explain why the concept of mechanical advantage is useful for engineers. Perform engineering design work in a group

4. Materials List Approximately 20 feet of nylon rope Two-wheeled pulley Single pulley Spring scale String Weight (200g, 500g, 1kg) 4 copies of the Pulley Worksheet

5. Introduction What are some examples of tools? (Answer: There are many different kinds of tools: hand tools, power tools, big tools, small tools, tools with specific uses, tools with many uses, and so on.)

6. Pulleys/MA We will attach the pulleys to the ceiling cross members using pipe cleaners.

7. What is the purpose of a pulley? Vertical Lifting. How do you measure a pulleys effectiveness? (Answer: We would calculate the mechanical advantage.)

8. Pre-Activity Assessment How many devices can you think of that contain pulleys? (Some examples include: assembly lines, cranes, construction sites and other places where heavy objects need to be moved.)

9. Procedure Stand on tables to hang the two-wheeled pulley on the ceiling, as shown in Figure 3.

10. Follow the instructions on the Pulley Worksheet for measuring the weight (load) of the object, effort and mechanical advantage of several pulley systems.

11. Safety Issues Be careful when standing on tables. If you would rather stand on a desk or not stand on anything please use your best judgment. If you need help attaching the pulley to the ceiling please raise your hand and ask for help.

12. Post-Activity Assessment Are the theoretical and actual mechanical advantages similar for each pulley system? Make a list of the problems, design requirements, and constraints. (Examples: budget for materials, time, safety and impact on the whale, ethical and social impacts.)