So on the 12 February, which was a Friday, we decided to test our bridge during the physics period that we had. Since Mr Tan Wei wasn't there, Mr Tan Hoe Teck took over the class and we went to the physics lab. There we checked the mass of our bridge. It was 240g. So we went straight into testing the bridge. Apparently, we didn't have hope that our bridge will carry over 15kg because of the lack of materials that we had. So we went to test our bridge. So Mr Tan placed the weighing platform on the bridge using a strap. The weighing platform is 10kg. Our bride showed no sign of breaking. So we were very hopeful that we can carry 15kg. But when the 5kg gym weight was placed, we heard our bridge breaking. Then suddenly, the bridge just broke off and the weighing platform just fell. So we were able to carry 10kg. We were happy about that even though we can't score as well as we thought but at least, we carried something.
Some Photos on the testing
The Video of testing our Bridge
Calculation of Efficiency
(a) Mass of load on bridge = 10 kilogram
(b) Mass of bridge = 0.24 kilogram
Efficiency = 10kg / 0.24kg= 41.6 No units
Discussion of bridge design after testing
1. What is your score on efficiency? If the efficiency is high/low, what went right/wrong?
We scored 42 points on efficiency. This efficiency is quite low compared to other groups in our class. So we think that we could have scored much better than this if we had not lost the previous bridge. Because the previous bridge, we used a lot of ice cream sticks to make it. So after losing the previous bridge, we realised that we did not have enough sticks. Thus, we had to work with the sticks which were remaining. We had to make a new bridge within one day. This wasn't easy because building the bridge in one day requires a lot of brainstorming, manpower and commitment. We had to focus on what we were doing. And so we made a bridge that withstands up to 10kg.
2. Which part of the bridge started to give way first? Explain using Physics concepts.
The Middle of the bridge started to give away first.
Since the most force asserted on the middle portion of the bridge, the surface area supporting the force is small thus the total pressure is bigger. Pressure is base on the total force over the surface area therefore the middle gave way first due to most pressure acting on it.
3. Which part of the bridge provided the most strength in the testing process? Explain using Physics concepts.
The middle part of the bridge provided most strength in the testing because the force is acted on the middle of the bridge and as newton's law state that every action has a reaction therefore the reaction force is exerted at the middle where most action took place there so the middle provided the most strength in testing.