Interactions and Machines

For all of the activities under this heading, you will need to download and read Interactions in Machines Part 1 activity sheet (pdf). Use the format in this sheet to analyze interactions in the machines you study, design or build.

If you have completed Unit 3 Cycle 1 Activity 12 (Simple Machines), you could also identify some or all of the simple machines that make up the more complex machine you studied, designed or built. Use the format outlined in Interactions in Machines Part 2 activity sheet (pdf).

Analysis of a Machine

Examine a machine in terms of interactions, energy and forces. The machine could be an electronic appliance, an engine, a purely mechanical device, or any other appropriate piece of hardware.

Find as many interactions as possible in the machine, and identify both the interacting objects and interaction types. After you identify the interactions, analyze the interactions using energy diagrams. For mechanical and gravitational interactions, draw force diagrams as well. For all interactions, provide evidence of the interactions. 

If you have completed Unit 4 Cycle 2 Activity 8, analyze the machine (especially an electrical device or an engine) for energy efficiency and describe how the energy efficiency of the device might be improved. See Interactions in Machines Part 2 activity sheet (pdf).

Partners: This activity is a good project for teams of two or more. Two or more partners might be able to probe the workings of a complex machine in greater depth than a single person could. 

Constructing a Machine

Design and/or build a Rube Goldberg-style machine and analyze it in terms of interactions, energy and/or forces. The basic idea behind a Rube Goldberg machine is that you build a complex machine to perform a simple task. See examples of Rube Goldberg machines on-line by doing a Google search using "Rube Goldberg" as your search criterion. You may do either a text search or an image search.

Identify as many interactions as possible in the machine you have designed or built. After you identify interaction types, analyze the interactions using energy diagrams. For mechanical and gravitational interactions, draw force diagrams as well. For all interactions, provide evidence of the interactions.

Partners: This activity is an ideal project for teams of two or three. If you look at some of the examples of Rube Goldberg machines available on-line, you'll notice that in general, they are both imaginative and rather silly. If you have a partner (or two), you have someone you can brainstorm with, and in all likelihood, you and your partner(s) would come up with a device that is both more inventive and ridiculous than you would come up with by yourself!

Mousetrap Cars

A mousetrap car is a toy car that uses only one mousetrap for propulsion. The goal of the assignment is to build a car that either goes the greatest distance or the fastest speed. You can start by researching "mousetrap cars" on-line (Google text search, image search). 

Then design and build a mousetrap car, and analyze your car in terms of efficiency identify the interactions, draw energy diagrams and draw force diagrams. If more than one student or team does this project, your teacher could stage a race between the cars and offer a small prize for the winner. Discuss how you would improve your design.

Identify the interactions that occur in the mousetrap car. After you identify interaction types, analyze the interactions using energy diagrams. For mechanical and gravitational interactions, draw force diagrams as well. For all interactions, provide evidence of the interactions.

Partners: This activity is a great two-person project. A partner gives you someone with whom you can brainstorm ideas, and work together to build the coolest, fastest or farthest-going car in your class!