## Uniform vertical circular motion

The following GeoGebra app simulates the force vectors on an object in uniform vertical circular motion.

A real world example of this would be the forces acting on a cabin in a ferris wheel.

<iframe scrolling="no" title="Vertical Uniform Circular Motion " src="https://www.geogebra.org/material/iframe/id/t5jstqsm/width/640/height/480/border/888888/sfsb/true/smb/false/stb/false/stbh/false/ai/false/asb/false/sri/true/rc/false/ld/false/sdz/false/ctl/false" width="640px" height="480px" style="border:0px;"> </iframe>

## Vertical Non-Uniform Circular Motion

This is a simulation that shows the vectors of forces acting on an object rolling in a vertical loop, assuming negligible friction.

To complete the loop, the initial velocity must be sufficiently high so that contact between the object and the track is maintained. When the contact force between the object and its looping track no longer exists, the object will drop from the loop.

The following code is for embedding in SLS.

<iframe scrolling="no" title="Vertical non-uniform circular motion" src="https://www.geogebra.org/material/iframe/id/ny3jhhsp/width/640/height/480/border/888888/sfsb/true/smb/false/stb/false/stbh/false/ai/false/asb/false/sri/true/rc/false/ld/false/sdz/false/ctl/false" width="640px" height="480px" style="border:0px;"> </iframe>

## Aircraft Turning in a Circle: a 3-D Visualisation with GeoGebra

This GeoGebra app is a 3-D visualisation tool of the force vectors acting on an aircraft turning with uniform circular motion in a horizontal plane.

I prepared this in advance as I will be lecturing on this JC1 topic next year.

## Hydrostatic Pressure and Upthrust

This app is used to demonstrate how a spherical object with a finite volume immersed in a fluid experiences an upthrust due to the differences in pressure around it.

Given that the centre of mass remains in the same position within the fluid, as the radius increases, the pressure due to the fluid above the object decreases while the pressure below increases. This is because hydrostatic pressure at a point is proportional to the height of the fluid above it.

It can also be used to show that when the volume becomes infinitesimal, the pressure acting in all directions is equal.

The following codes can be used to embed this into SLS.

<iframe scrolling="no" title="Hydrostatic Pressure and Upthrust" src="https://www.geogebra.org/material/iframe/id/xxeyzkqq/width/640/height/480/border/888888/sfsb/true/smb/false/stb/false/stbh/false/ai/false/asb/false/sri/false/rc/false/ld/false/sdz/false/ctl/false" width="640px" height="480px" style="border:0px;"> </iframe>

## Micro:bit Line-Following Robot

I was looking for an extension to the Micro:bit Go set that I bought a while back and came across a robot set that is currently on sale. This set comes with most of the sensors a typical line following or obstacle avoiding robot needs. Currently, it is being sold at a fraction of the price of other similar Micro:bit robots, and is far cheaper than sets such as the Lego EV3.

After unpacking it earlier this evening after work, I managed to put together the parts by following the instructions, which were quite clear.

1. Micro:bit Go (S$30 on Lazada) 2. Yahboom Micro:bit Robot (selling for S$49.68 only at Lazada)

To program the robot using Micro:bit's Makecode, which is a block programming interface that is very similar to Scratch, you will need to download the Yahboom blocks by selecting Extensions from the Advanced menu.

Enter the following URL into the search bar: https://github.com/lzty634158/yahboom_mbit_en

You will then see the library of new blocks including those meant for the robot below:

A few simple lines of code are all that is needed for the light sensors to keep tracking a black line by turning whenever one of the sensors detect white while the other detects black.

After programming the robot, download the hex file into the Microbit and the robot is good to go.

## Javascript Game to Learn How to Count Money

Trying to brush up my Javascript skills after being inspired by one of the senior specialists in ETD, I created this simple Javascript Game to teach kids how to count money using Singapore coins.

To play this game, click or press the "Play Button". Click on the coins to make up the targeted amount. Be careful as the coins will move over one another.

This is meant for children entering primary one soon so that they can learn how to pay for food at the canteen.

## GeoGebra in SLS

1. update on 2 Jul 2019: The SLS lesson shared during IPSG 2019 can now be found in the SLS Community Gallery.
2. Join the local community of GeoGebra users at: https://www.geogebra.org/group/stream/id/VFX2EG8xa
3. GeoGebra tutorials at: https://www.geogebra.org/m/Ebm5wBW5  (Start with Geometry and Functions & Graphing)
4. GeoGebra apps curated for A-level Physics: https://www.geogebra.org/m/dgedzmz3
5. GeoGebra apps curated for O-level Physics: https://www.geogebra.org/m/z5nfs8qd
6. IPSG Poster on "An SLS Learning Experience with GeoGebra Apps on the First Law of Thermodynamics"
7. Instructions on how to embed GeoGebra into SLS.
8. Let us know if you have used or adapted the SLS lesson, or if you have ideas for new GeoGebra apps in the comment section below.

## Geogebra Simulation of a Potentiometer

Some of the more challenging problems in the topic of electricity in the A-level syllabus are those involving a potentiometer. The solution involves the concept of potential divider and the setup can be used to measure emf or potential difference across a variety of circuits components. Basically, students need to understand the rule - that the potential difference across a device is simply a fraction of the circuit's emf, and that fraction is equal to the resistance of the device over the total resistance of the circuit.

$V_{device}=\frac{R_{device}}{R_{total}}*emf$

The intention of this Geogebra app is for students to practise working on their calculations, as well as to reinforce their understanding of the principle by which the potentiometer works.