WOOD TOWER DESIGNS Objective: Students will be able to construct a tower out of wood in order to investigate the physics of structures.

Towers are antennas.

Towers are Buildings.

Towers support power lines.

Towers are support wind power.

Towers hold clean water.

Towers are vertical structures.

Towers are shaped differently.

TOWER REQUIREMENTS Tower teams of up to two members The structure must have the minimum dimensions of (a) height – 14 inches The structure must weigh no more than 2 pounds. The structure may be of wood only. Any type of standard white glue may be used, nails, etc., are left to the discretion of the builder.

TOWER REQUIREMENTS Before the test of the Tower, each team must promote their tower - give a sales pitch to the public (2 minutes time limit strictly enforced). The weights loading and testing apparatus will be provided. The weights may be added in any order. The structure must support the weight for five seconds.

GRADING RUBRIC A = Over 100 B = 99 – 90 C = 89 – 80 D = 79 – 70 Pounds Towers must support a minimum of 69 pounds A = Over 100 B = 99 – 90 C = 89 – 80 D = 79 – 70 Pounds E = 69 pounds or less

JUDGING The structure supporting its weight will be given points based on the grading rubric. The sales pitch will be worth 100 points, with the judges' decision to be based on features such as oral skills, knowledge of physical science, audience appeal, etc...

GRADING RUBRIC TOTAL = 1400 Points Extended Constructed Response (1) – 200 pts Brief Constructed Responses (3) – 300 pts Sales Pitch (Oral Presentation) (1) – 100 pts Warm Up Assignments (6) – 600 pts Tower Building Participation (1) – 100 pts Tower Test (1) – 100 pts TOTAL = 1400 Points

WARM UP ASSIGNMENTS Create a daily plan of action This is a 4-5 sentence statement about what the group intends to do that day. Every group member must complete a daily plan of action that shows how they plan to contribute to the group. Each plan of action must include all actions and show a progression every day.

BRIEF CONSTRUCTED RESPONSE #4 Watch the video on www.youtube.com and comment on the strength of the tower presented. Write a statement about how the tower has succeeded (what principles of physics) to carry the designated weight. Http://www.youtube.com/watch?v=CkCmtaPepww

BRIEF CONSTRUCTED RESPONSE #2 Write a four to five sentence statement about how your group plans to support the selected weight. Explain your design concepts (structural design) and building plans (construction methods) to complete your project.

BRIEF CONSTRUCTED RESPONSE #3 Compare your tower design to another group. Explain the similarities or differences in your design as compared to their design. Take into account construction, design, symmetry, joints, and shape.

EXTENDED CONSTRUCTED RESPONSES #1 You have been hired to complete a water tower for the city of Hyattsvilleburg, Maryland. The tower must carry three times it’s previous weight because of the increase in residents. Explain how your tower will support the weight of the increase in water. Use scientific principles in your explanation.

BRIEF CONSTRUCTED RESPONSE #1 Watch the video on www.youtube.com and comment on the strength of the tower presented. Write a statement about how the tower has succeeded (what principles of physics) to carry the designated weight. Http://www.youtube.com/watch?v=CkCmtaPepww

TOWER DESIGNS Engineering students frequently use wood to build model structures and then test them for weight-bearing capacities. The best wood tower designs incorporate some basic engineering principles.

TOWER DESIGNS

TOWER DESIGNS

TOWER DESIGNS

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TOWER TIPS

Structural Shapes The best wood tower designs use basic structural shapes, such as triangles, whose firmness allows them to support weight in a secure fashion. Squares and other polygons can also be used in tower designs, but require support if they are to bear weight without twisting and giving way.

Joint Types A good wood tower design incorporates several types of joints to help increase its tensile strength. Butt joints are the simplest of joints as they simply consist of two members butted together and adhered with glue. Lap joints, on the other hand, use an overlapping method to join two pieces of wood or other material and offer greater stability.

Symmetry Symmetry is essential to an excellent wood tower design. It is a good idea to form each one of the two main sides of a tower as they rest directly on top of one another.

Adhesives The best wood tower designs require the sparing use of glue and other liquid adhesives. Many competitions require you to have your tower weighed, and excessive glue adds a considerable amount of additional mass to a tower. Do not use glue to fill gaps, and make sure all measurements are exact.

Tensile Strength Pre-tests are important in determining good balsa wood tower designs. Strips differ in weight-bearing strengths, or tensile strengths, and it is important to group similar pieces together. During the final assembly of the tower, the strongest pieces will be most suitable for the longest parts of the structure, while weaker pieces better support shorter portions.

INSTRUCTIONS Diagram the tower using the grid paper to give you scale: one grid square represents 1 square inch, for example. Start with the base of your structure, making it wide to keep the center of gravity low. Design the exterior structure. Don't forget the rules of the competition, but feel free to brainstorm a little. When you have a design you like, make diagrams for several angles of the design--at least a front, side and three-quarters-rotation view.

INSTRUCTIONS Use the diagram to figure out how forces, like gravity and competition weights, will push or pull on the tower, and imagine how that will stress the various parts of the tower. Add a system of supports to counteract this: most buildings are built in layers with a series of triangular trusses that hold the structure together.

INSTRUCTIONS Measure, mark and cut the base pieces for your structure. Miter them if you can, this will give more surface area to glue and make the structure hold together more cleanly. Don't mash the wood as you cut; this will damage the fibers of the wood and make the structure weaker.

INSTRUCTIONS Glue the pieces together. Hold them together until the glue is dry. Measure and cut the next layer of pieces. Glue them onto the base, and hold until dry. Repeat this process until you have built the tower. If you find a weakness while building, add a strut as necessary, but stick to your diagram as much as possible.

INSTRUCTIONS Leave the tower to dry overnight. Test it with a light weight, to see if the glue is holding. If the structure has any damage, repair it and find ways to strengthen it.

START PLANNING, DESIGNING, & BUILDING.