ZIMSEC O Level Combined Science Notes:Experiment: Comparing roof truss structures
Aim: To determine which structure is best for roof trusses/bridge girders
Materials: Poplar wood /ice cream sticks/grass straws, stikistuff/drawing pins/glue, tin of sand, 2 bricks, weighing scales
- Build models of roof trusses and bridge girder using ice cream sticks/grass straws or poplar wood
- Support each structure on bricks at the two thrust points
- Load each of at the point shown by the load arrow using the tin of sand
- Find the load each structure can carry by weighing the sand in the tin at the moment the structure breaks
- Repeat this for each structure
- Ty to determine which beams are in compression ( the ones that collapse in inwards)
- And which ones are in compression (the ones that collapse outwards
Observations and Results
- For house roof structure d holds the most load before collapsing.
- Structure c holds slightly less weight when compared to d followed by structure b which holds less weight
- Structure a holds the least weight before giving in
- Structure f holds more weight compared to structure e which is susceptible to shear forces
- Structures d and f hold the most weight
To access more topics go to the Combined Science Notes page.
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