# Mechanics Models

Some of the most foundational concepts of civil engineering are taught during a student's first year of studies. Among these concepts are the physics of everyday structures, such as arches and dams. Traditionally, these are taught in lecture, with little to no interactive components. As physics is a concept-based subject, a collection of activities was created to teach these concepts to students through hand-on activities and physical models.

## Overview

Students will work through 13 carefully formulated activities in an opportunity to connect concepts learned in class with physical models. These concepts include the strategic construction of silos, culverts, dams, retaining walls, arches, and gothic cathedrals. Each activity with its own unique setup, concept, and materials, allows students to delve into each topic, first by predicting results, then by testing their hypotheses. The students are tasked with testing not only their own predictions, but also a few counter-intuitive hypotheses, in order to fully illustrate concepts in their elemental nature: forces in equilibrium. Students then reflect on how the lessons learned relate to earlier assumptions and the concepts taught in class.

The activities are listed below:

## Activities

### Stacking Blocks

Students are challenged to compete in teams of 4 to produce a design with the largest overhang. Students will have the opportunity to feel the varying vertical forces acting on the blocks and predict whether or not their design will stand.

### Beam Statics

Students will apply various loads and moments to a wooden beam, and monitor the resulting effects on the beam. Using weigh scales and a torque tool, they will learn how loads and moments – and their applied locations – affect the support forces (reactions) associated with simply-supported beams.

### Equilibrium at a Point

Students will investigate equilibrium of a point (a small metal ring) under the action of forces from 1, 2, 3 and 4 spring scales. They will find that the vector sum of the forces at a point must add to zero for it to remain in equilibrium.

### Equilibrium on a Rigid Body

Students will investigate equilibrium of a rigid body by applying forces from 1, 2, 3 and 4 spring scales. As the students move the scales and change the forces they carry, they will see that the Principle of Concurrent forces is always satisfied (unless any of the forces are parallel).

### Tanks

Students will get a chance to feel the forces present in a circular tank or silo at varying depths. Through this, they will learn the physics behind why many vertical tanks and silos have added circumferential reinforcing along their lower sections.

### Culverts

Students will experiment with different culvert designs of their choice, along with those used in professional practice. They will also have the opportunity to observe the consequences of appropriate versus unsuitable backfilling procedures.

### Dams

Students will have the opportunity to hypothesize the affects that different loads have on a basic dam structure. Students will then build and test several different dam designs, and contemplate why some work better than others.

### Retaining Walls

Students will have the chance to test a variety of retaining wall designs. They will compare the strength of walls with different bases and find which design is most effective and why.

### Arches

Students will build a series of arch designs, some of which stand on their own and some which do not. Through this, they will learn about the factors that affect the ability of an arch to be free standing- such as the shape and thickness.

### Gothic Cathedrals

Students will assemble a series of Gothic Cathedrals and discover that building components must be assembled in a certain order to prevent collapse during construction. They will also learn about the different structural components and other strategies for counteracting lateral forces.

### Suspension Bridges

Students will encounter the challenges of building a long-span bridge when they cannot supply materials or support from below. They will also consider how the various components must be assembled in proper sequence and work together as a structural system.

### Beam Deflection

Students will build a series of point-loaded beams with various boundary conditions and observe the resulting deflections. Accompanying spreadsheets will allow them to study how load, deflection, slope, moment, and shear are related to each other.

### Domes

Using this model, students will see how the blocks in a masonry or snow dome fit together to make a stable structure. The dome segments are linked together with elastic cords so that various modes of buckling can also be demonstrated.