My experiment.

"How the designs of a Truss bridge affect its durability and ability to withstand the most weight."

Aim: To determine which Truss bridge design can withstand the most weight and is most durable.

Hypothesis: The bridge design - Howe - will be the most durable and can withstand the most weight.

Equipment:
-scale
-paddlepop sticks ( to build my bridges)
-hot glue gun or weldbond glue
-two books of the same height
-myself
___________________________
-bricks

Method 1:
I will use the bridge designs from my previous post, building three of each of the four designs.
I will then test their strengths and durability.
To do this I will lay the bridge between the two books and a scale on top of the bridge.
I will then proceed to place my first foot on the scale and then my second, looking at the scale to when it collapses.
I will record the results and repeat the process with the other bridge designs.

Method 2:
Instead of using a scale and placing my weight on top. I will use bricks.
I will first weigh the bricks then place them carefully one by one on the bridge until it collapses.

Independant variables
-Bridge design
-My weight
-Amount of glue
_____________________
-Bricks

Dependent variables
-Durability of bridge

Controlled variables
-Paddlepop sticks (should all be the same)
-Height of books
-Lengths of bridges
-Weight of scale (will be the same scale)
-Holding power of glue ( will be the same glue)
__________________________________
-Weight of bricks

A watched a video on this site:
www.garrettsbridges.com/videos/make-magazine-make-bridges
It really gave me inspiration as to how I would carry out my experiement. Credits to Garrett.

He demonstrated how to build a paddlepop bridge and screened his contest of bridges built by amateurs and professionals. They all stood on their bridges using my "method 1" and most of them succeeded.