“Strongest Bridge”
Student Learning Objectives:
- Construct a bridge that can hold the most weight
- Apply gravity to engineering design
Materials (per team):1 lb box Spaghetti (same regular/thin for each team)
1 roll ½ inch Masking Tape
1 material chosen and provided by student team
(such as string, glue, package of rubber bands, etc.)
Access to several rolls Pennies
Introduction:
Gravity causes objects to have weight. In order to stop an object form accelerating downward, there must be an upward support force. When the object is stationary, it means the forces are balanced, the forces acting in opposite directions are equal. The amount of support force provided depends on the materials used and construction techniques.
Preliminary Question:
A. Make a sketch to show the direction of the gravitational force and the direction of the support force for a roll of pennies sitting on a table.
Rules for the Bridge:
- Your bridge must be at least 2 inches above the table.
- All penny rolls must be stacked in some way on the center of the bridge when testing strength
- Penny rolls must be able to layand stack on your bridge on their own (hands off)
Procedures:
Your team will be designing and constructing a bridge out of spaghetti to hold rolls of pennies.
1. Read all procedures (2-8) before you begin any experimenting. Then carefully read each step as your team completes this activity. Take turns, alternate, using the materials and making observations.
2. Obtain one roll of pennies. Hold it and feel its weight.
3. Discuss how you will design your bridge. Consider the properties of the building materials and how you will use them to construct a strong bridge that may hold maximum weight. Also, consider how you will place the rolls of pennies once the bridge is complete; the rolls of pennies must be able to sit on the bridge on their own (without you holding them). If there are different ideas about how to do this on your team, the team must find a way to come to a consensus.
4. Write the plan for constructing your team bridge. The plan should include a sketch and the steps for construction of the bridge. Divide the steps among the team so that each person has a role in constructing the bridge.
5. Follow your team plan and construct your team bridge, following the rules for the bridge.
6. Place the roll of pennies on your bridge. If the bridge holds, then obtain additional rolls of pennies. Remember that the rolls of pennies but be horizontal, lying down.
HorizontalNot Vertical
7. Stack rolls of pennies on the center of your bridge, until your bridge breaks, or until added rolls of pennies will not stay on your bridge without falling off. All rolls must be oriented horizontally. Record the number of rolls your team bridge supported prior to breaking or prior to added rolls falling off. If your bridge is able to hold 12 rolls without breaking, and without the rolls falling off the bridge, then record that your bridge supports “12 or more” rolls of pennies
8. Clean up:
- Return Masking Tape and Rolls of Pennies to designated places.
- Clean up all pieces of your team bridge and throw it in the trash (unless otherwise instructed)
Analysis & General Questions:
1) Discuss the design features of the strongest bridge. Compare this bridge to your team’s bridge and describe the differences. If your team had the strongest bridge, describe the features of your bridge that you think contributed to supporting the most rolls of pennies.
2) Compare the design of your bridge to a bridge for cars. Name some similarities and differences.
Ciardi, TStrongest Bridge1