Classroom Activities
Activity 1: Power Point Presentation on Bridges
The following culminating activity is designed for the first two sections of this curriculum unit, the history of bridges and the types of bridges. The behavioral objectives incorporate both pedagogical and content specific skills. The pedagogical skills involve: the ability of the students to work cooperatively in groups, the proficiency of the students to summarize material, and their ability to use computer software. The content specific skills are based on an understanding of the development of bridges as an effect of advances in civilization. Working in cooperative learning groups comprised of four students, each group will create a fifteen minute power point presentation on a specific type of bridge. The presentation will focus on the historical development and examples of that specific type of bridge. In addition, the presentation will examine the function and/or situation for which that type of bridge is best suited while considering the underlying factors which would influence its use.
Activity 2: Graphical Analysis of Young's Modulus of Elasticity
The behavioral objectives for this activity involve the students' ability to: distinguish independent variables from dependent variables, create appropriate scales, use data in creating a graph, calculate the slope of a line, and determine its significance. Using the data listed in Table 1, the students will graph stress (P/A) verses the strain (ΔL/L) for a series of metals, calculate the slope for each, and determine the percentage error between the calculated value and the accepted value of Young's Modulus for each metal.
Table 1: Values are listed below for the stress (P/A), strain (ΔL/L), and Young's Modulus for a number of selected metals.
Aluminum
| Sample 1 | Sample 2 | Sample 3 | Sample 4 |
| P/A = 7.30x10^7 | P/A = 14.6x10^7 | P/A = 21.9x10^7 | P/A = 29.0x10^7 |
| ΔL/L = 1.00x10^-3 | ΔL/L = 2.00x10^-3 | ΔL/L = 3.00x10^-3 | ΔL/L = 3.97x10^-3 |
(The units for P/A are N/m 2)
Young's Modulus for aluminum = 7.3x10 1 0 N/m 2
Brass
| Sample 1 | Sample 2 | Sample 3 | Sample 4 |
| P/A = 2.1x10^7 | P/A =5.7x10^7 | P/A = 7.2x10^7 | P/A = 10.3x10^7 |
| ΔL/L = 0.29x10^-3 | ΔL/L = 0.55x10^-3 | ΔL/L = 0.70x10^-3 | ΔL/L = 1.00x10^-3 |
Young's Modulus for brass = 10.3x10 1 0 N/m 2
Magnesium
| Sample 1 | Sample 2 | Sample 3 | Sample 4 |
| P/A = 4.5x10^7 | P/A = 7.2x10^7 | P/A = 9.9x10^7 | P/A = 13.5x10^7 |
| ΔL/L = 1.0x10^-3 | ΔL/L = 1.6x10^-3 | ΔL/L = 2.2x10^-3 | ΔL/L = 3.0x10^-3 |
Young's Modulus for magnesium = 4.5x10 1 0 N/m 2
Steel (High Carbon)
| Sample 1 | Sample 2 | Sample 3 | Sample 4 |
| P/A = 4.1x10^7 | P/A = 16.5x10^7 | P/A = 31.0x10^7 | P/A = 41.4x10^7 |
| ΔL/L = 0.2x10^-3 | ΔL/L = 0.8x10^-3 | ΔL/L = 1.5x10^-3 | ΔL/L = 2.0x10^-3 |
Young's Modulus for steel (high carbon) = 20.7x10 1 0 N/m
Activity 3: Truss Bridge Problems
The behavioral objectives for this activity include students being able to solve static equilibrium problems, draw free body diagrams, resolve vectors mathematically, and distinguish compression forces from tension forces within a given truss bridge structure. Given the truss structure in Figure 1, the students should be able to calculate the external forces F A and F E at points A and E. In addition, they should be able to calculate the internal forces between members A-B, A-C, B-D, and B-C. They should also be able to determine whether those members are in compression or tension.
Figure 1: Truss Bridge Diagram (all angles are 60º)
Activity 4: Build a Bridge
The behavioral objectives for this final activity center on the ability of the students to apply their knowledge of bridge design and physics in constructing a scale model of a bridge. They may choose from any of the following: beam, arch, truss, cantilever, suspension, or cable-stayed design. The bridge is to be constructed from wood with the dimensions not to exceed 24 inches in length, 4 inches in width, and 12 inches in height. Prior to the actual construction of the bridge, a scale drawing of the bridge must be submitted.
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