The bridge will support a load applied from above by a loading plate that has a $70$ mm x $70$ mm square surface area $($see Fig. $1).$ The load will be applied using a Hounsfield universal testing machine fitted

with a jig that can support the bridge from below. The Hounsfield universal testing machine and jig will be used to mechanically test the maximum load of the bridges. The loading plate will be lowered slowly at a speed of $500$ mm$/$min$.$ lamination$/$ glueing of the balsa to make thicker members is not allowed. Gusset joints are permitted, and the material used should be from the balsa wood supplied. The length of any gusset joints should be less than $10$ mm$.$

Each group will be provided with

$2$ lengths $($each of approximately $900$ mm$)$ of $5$ mm square balsa

$2$ lengths $($each length approximately $900$ mm$)$ of $3$ mm square balsa

Bridge Specs:

$-$Top length: $150$ mm

$-$ Bottom Length: $200$mm

$-$ Width: $70$mm

$-$ Height: Max $100$mm

QUESTION:

$1.$ how many $3$x$3$mm and $5$x$5$ members we need to build it$?($also try to use the $5$x$5$ for the $150$mm and $200$mm parts$)$

$2.$ Calculate tensile$/$compressive loads in each member $($structure support $100$N load$)($make a table also including the pieces used as gusset joints$)$

$3.$ Find maximum loads for each member $+$ reasoning $>$ Which will fail first?