4.1 - Testing
4.2 - Calculation of Efficiency
(a) Mass of load on bridge =
(b) Mass of bridge =
Efficiency = (a) / (b)
4.3 - Discussion of Bridge design after testing
1. What is your score on efficiency? If the efficiency is high/low, what went right/wrong?
The group’s efficiency score is 114. The efficiency is rather low. About 80% of the mass applied onto the bridge was distributed onto the base and not to the truss system. The glue managed to hold the members of the bridge together but it is not able to help “pull” the truss downwards to help distribute the mass.
2. Which part of the bridge started to give way first? Explain using Physics concepts.
The centre portion of the bridge or the base gave way first. The base was not able to distribute the mass to the other members of the truss by the concept of tension. The glue was not strong enough to “stretch” the truss downwards. Thus there was also no tension or compression in the truss, only having the base to withstand most of the mass.
3.Which part of the bridge provided the most strength in the testing process? Explain using Physics concepts.
The part of the bridge that provided the most strength is the base as it took most of the mass. It managed to take 30kg before breaking. I do believe its due to the specific way we glued the sticks together, vertically. By placing the sticks vertically, it has lesser exposed surface area compared to them being glued together horizontally. We hope to lessen the pressure as in the formula (P=F/A) the surface area place a very big role. So by placing them vertically we reduce the pressure applied to each ice-cream stick and also increases the number of ice cream sticks glued together which increases the strength of the base too.