Sum It Up: An Introduction to Static Equilibrium
Students are introduced to static equilibrium by learning how forces and torques are balanced in a well-designed engineering structure. A tower crane is presented as a simplified two-dimensional case. Using Popsicle sticks and hot glue, student teams design, build and test a simple tower crane model according to these principles, ending with a team competition.
Figure 1. Example completed tower crane designed and built by a student team.
Having an understanding of equilibrium is critical for engineers and scientists. Buildings, bridges, and other structures remain standing because engineers design them to meet equilibrium conditions, in which all of the forces acting on the structures are balanced.
After this activity, students should be able to:
- Understand the concept of static equilibrium.
- Identify and model, with free-body diagrams, forces in two dimensions (x-y plane) and torques about a point.
- Model why and how equilibrium occurs for a two-dimensional shape.
- Understand how forces and torques must sum to zero in order for an object to remain in static equilibrium.
- Use multiple equations to solve for unknown variables.