Physics and Astronomy

Bridge That Gap
Objective To construct the most efficient structure, spanning between two surfaces, capable of carrying a mid-span concentrated load while meeting the required construction.
Participants Teams of up to four.

The structures must be built from the following materials: drinking straws, string, masking tape.


The efficiency E of the structure will be the total load carried, P, divided by the total weight of the structure, W. E=P/W

1. The structure must be a stable system and capable of being lifted without collapse when independent of the support surfaces, described below.
2. No portion of the unloaded structure shall protrude below the elevation of` the supporting surfaces.
3. A loop of string, capable of carrying more than the anticipated collapse load, must be attached to the mid-span of the structure.


1. The supporting surfaces will be two horizontal tables separated by a clear distance of 500 mm., and supplied at the test site. (See Figure 1.)
2. The concentrated load will consist of a juice container to which a hook will be fastened which will be attached to the mid-span of the structure. Weight will be added in a continuous manner until collapse (failure) occurs.
3. One structure only may be submitted for test. The structure will be weighed on a pan balance, to determine the value of W, before being tested.
4. The structure will be placed on the supporting surfaces by one member of the team.
5. The juice container will be attached to the structure by one member of the team.
6. Load will be added to the container by the chief judge.
7. At failure, the weight of the container plus any added weight will be recorded and will be the load P.
8. The efficiency will be calculated by the chief judge.
9. The winning entry will be the structure with the greatest efficiency.

Source Technical University of Nova Scotia.

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