Scenario Presentation 2

We had the rest of the scenario presentations. There were 3 groups left. The first group had this scenario: In a production line, 10000 small screws are to be sorted into packs of 50 each. Manual counting would be too tedious. Suggest ways in which the sorting may be done.

This problem seems quite tricky. However, if you think hard about it, the solution is actually pretty simple.


The group had two solutions. 1. Use an electromagnet. Adjust the resistance of the electromagnet such that it attracts 50 screws each time. However, Mr. Lim said that this solution was not very relevant as the electromagnet would be likely to attract either all the screws or none at all. Hence, this solution was not likely to work.


2. Use a weighing scale. Count the first 50 screws and weigh them. Subsequently, grab a handful of screws and weigh them. Compare the reading to the first reading of 50 screw and adjust the number of screws accordingly. This solution is both practical and feasible. It is based on how shopkeepers weigh biscuits or ham using the weighing scale and add more or take out some based on the weight of the products.


The next group had a relatively more common scenario, but explaining it was more difficult. This was their problem: A spring balance will give a different reading on the Moon than from that on Earth. A beam balance, however, will give the same reading. Explain why.


The group's answer is as follows: A spring balance measures weight, which is dependant on gravity. The Moon has less gravity than the Earth, hence the reading differs. However, a beam balance measures mass, which is constant no matter what. Short and sweet, but very clear.


The final group had a very interesting topic. How do submarines float and sink at will?


In my opinion, this group had the most detailed presentation. They explained how air is pumped into the ballast tanks to force water out so that the submarine would float. On top of that, they included a lot of other information such as diagrams, and information on the Kursk Russian submarine disaster. They talked about how a faulty Dummy torpedo had allowed flammable liquid to leak through and explode the front of the submarine, letting water in and causing the submarine to sink.

At the end of the presentation, they gave us question to think about: If a submarine sinks to the seabed, why is it no longer available to move off? The answer is that there is no water under the submarine to create a lift force, hence the submarine is stuck there until rescue workers drop a rope down to haul it back up. I enjoyed this group's presentation the most.

I enjoy thought-provoking lessons and topics like the ones Mr. Lim gave us. I hope we'll be able to have more of such lessons in the future.