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12 September

Lift on an Aerofoil: Coanda Effect, not Bernoulli

Seng Kwang Tan Blog 0 Comments

The commonly taught explanation (for people from my generation) for how airplanes generate lift often relies on the Bernoulli Principle, which states that faster airflow over the curved top of a wing reduces pressure, creating lift. However, this explanation oversimplifies the complex physics involved and is labelled an inaccurate theory by NASA. The true mechanism behind lift is better explained by the Coanda Effect, which describes how a fluid, like air, tends to follow a curved surface, such as an aerofoil.

In this video, John Collins (award winning paper airplane maker and author) explains how the Coanda Effect ensures that airflow stays attached to the wing’s surface, curving around it and being deflected downward. This downward deflection of air is critical because, according to Newton’s Third Law of Motion, the downward push of air results in an equal and opposite upward force—lift.

Understanding the Coanda Effect gives a more accurate picture of how lift is generated and explains why certain wing shapes and angles are more effective. Unlike the Bernoulli-based explanation, the Coanda Effect shows why airflow remains attached to the wing, ensuring the necessary conditions for lift.

13 June

How Nuclear Fusion can be achieved

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Helion Energy is currently aiming to produce nuclear fusion energy commercially by 2028. The idea behind how it intends to do so is well-described in the video above.

Imagine one glass of D20 generating 9 GWh of electrical energy – enough power for a home for 865 years, at a cost of 1 cent per kWh. If successful, it will be a significant source of green energy in the next 10-20 years.

More importantly, nuclear fusion energy could potentially address the fears of many with regards to nuclear fission energy, such as the possibility of catastrophic meltdowns, weaponisation of raw material and environmental impact of mining and disposing of nuclear waste. This is because nuclear fusion reactions are self-limiting in that the reactors will shut down automatically if the optimal conditions are not maintained.

I can’t wait to see this happen, if it happens. Other than solving much of the world’s energy problems, it will also open up new opportunities in the energy sector for scientists and engineering. In fact, Helion itself is recruiting quite aggressively now.

09 June

UX design considerations for GeoGebra apps

Seng Kwang Tan Blog, GeoGebra 0 Comments

Having started with making interactive simulations or visualisation apps with Easy JavaScript Simulations (EJsS) under the guidance of Senior Specialist Lawrence Wee from ETD in Nov 2016, I next learnt about GeoGebra in 2017 from my ETD colleagues who taught Math (shoutout to Loh Yan Xiang and Toh Wee Teck). I would like to share via this post a few guidelines that I have come up with when designing interactive apps for students

1. Fast and Minimalist Designs

Since picking up the necessary skills, I have been generating a number of interactives during my free time in preparation for my eventual return to teaching after my stint in ETD from Jun 2017 to Dec 2019. I continued to do so, often in tandem with the upcoming topics that I need to teach for JC1 and IP3 Physics – mainly Mechanics topics.

To balance creation of apps with fulfilling all my other duties, I needed to produce them in a minimalist and very targeted just-in-time manner. Working off templates help a lot as I do not have to redesign the buttons or re-code the animations triggered by the buttons. There is no need to spend one whole day working on an app to beautify it if all it needs to do is to demonstrate the motion of an object based on its acceleration-time graph, for instance.

2. Start with the Minimum Viable Product.

Most of the time, I need to go off to class with a minimum viable product (MVP) in software development speak – a workable no-frills version of the interactive that communicates the ideas or allows the visualisation that I intended. This will then allow me to receive quick feedback from my students on what works and what does not. I will then be able to make quick changes before the next class or in preparation for the next cycle of teaching.

3. Avoid Overloading Interactive Elements

I am a strong believer in displaying just enough buttons and sliders to do the trick. Each app should not have more than 3-4 interactive elements to avoid distracting the students from the main relationships or interactions that they need to learn.

The use of GeoGebra allows for me to make quick clones of an app and then modify it quickly to generate a new scenario, instead of adding more interactive elements to allow for multiple scenarios within a single app.

I also try to avoid giving too much information on the app itself, as I feel the content delivery should be done outside of the app, whether via the Student Learning Space, Google Classroom or even face-to-face classroom interactions.

4. Optimising for Small Screens

I try to keep to an app size of 640 px wide by 480 px height so as to optimise the app for the Student Learning Space. These dimensions also make it easy for students to view and interact with the app from their mobile phones, even when held in portrait mode.

5. Use Pastel Colours

Instead of using the traditional bold primary colours, I try to use pastel colours or more “soothing” colours to highlight key information or elements. These are the softer versions of the primary colours and I prefer to use them as it gives the key elements a pleasant accent despite the rest of the app being mainly grey, black and white.

27 January

Simulation on the effect of vaccination on the spread of Covid-19

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My ex-colleague Lawrence did a simplified simulation on how vaccination can work to slow down the spread of Covid-19. It shows a clear correlation between rate of transmission and percentage vaccinated. Of course, experts recommend 80% vaccination rate but every bit counts as you can see from the simulation. I will be sure to receive mine when we get our turn.

It could also be useful for educating the public on the continued need for social distancing/masks despite having a sizeable population being vaccinated.

(Note: p = probability of spread upon contact, and you can use the dropdown menu to select different modes of safe management measures)
21 July

Hydraulic Elevator

Seng Kwang Tan Blog, IP3 05 Density and Pressure 0 Comments

This is a hydraulic lift kit for kids that was purchased online for only S$2.10 from Shopee, with free shipping! I am not, in anyway, affiliated to this, but simply sharing about one of several fun and cheap educational sets that I bought to occupy my kids during this mid-term break.

Other than the syringe, joints and tube, the parts are mainly laser-cut from a piece of wood with a thickness of two millimetres. The instructions come with pictures for each step so even though the words are in Chinese, there is no need to read them.

This kit demonstrates Pascal’s principle which states that a pressure change in one part of a closed container is transmitted without loss to every part. Hence, the pressure change is transmitted from one syringe to another, allowing work to be done. Do not expect it to lift up very heavy weights, though as the syringes are not perfectly sealed.

I shall share about other kits that I bought for this break soon, including a $6.62 Tesla coil that I am looking forward to testing.

08 July

Documenting this website’s migration

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After years of hosting my website on a traditional webhosting service that has seen multiple service disruption over the years, I have switched to Amazon Web Services, which is more reliable and scaleable. I want my students to be able to access new features in my website with faster loading speeds. AWS is much harder to set up as there is so much to learn and a lot of SSH commands to key in. The first key decision is to decide whether an EC2 or Lightsail instance is better suited to my needs. In the end, I decided to go with Lightsail as it seemed easier to update the necessary DNS records.

One of the first features I am experimenting with is a Udemy-style LMS plugin that allows me to create lessons and quizzes within a course structure and comes with a mobile-friendly user-interface. I wanted a platform in which my GeoGebra apps, as well as other online resources such as YouTube videos, can be stitched together for students to review or learn new topics at their own pace, as well as for classroom activities.

I initially wanted to use LearnPress, a fuss free and user-friendly plugin for this purpose, and even designed a course within it. However, I soon realise that it does not have a feature for analysis of students’ results. So now I have installed Tutor LMS and will be putting in content soon. Tutor LMS also comes with many more question types including ordering and fill-in-the-blank.

I experimented with Google OAuth in another Lightsail instance and will be implementing it here so my students can log in using their school gmail account.

The next necessary plugin was Mathjax for LaTex input. I needed to make some edits to the lesson sidebar in the Tutor LMS plugin in order to fix a bug that prevents the equations from rendering when navigating using the sidebar.

I have also updated some CSS to customise the Tutor LMS pages to fit the general style of my current website theme.