Catapult

As part of a Bachelor of Education one of the units required groups of three to teach a curricular subject by creating a learning activity that uses digital technology. The technology of 3D printing was found to be beneficial to learning and teaching in the 21st century.

My group created an activity that consisted of multiple elements of technology including, the 3D model program ‘Tinkercad’, a 3D printer and the software ‘Tracker’. The purpose of the activity was to investigate Newton’s Second Law of Motion, ‘Force = Mass x Acceleration’, by students designing and creating catapults.

Let's see the Catapult in action first!

To design the catapult the 3D model program ‘Tinkercad’ was used. Tinkercad is a free, easy to use app for 3D design, electronics, and coding. When making a profile there is a simple step-by-step guide on how to use all of the functions such as, how to select shapes, group shapes together, cut out parts of shapes, control the viewing camera, resize the objects and change the colours. During the design process to have a working catapult it needed to be broken into two individual parts and joined together once printed.

The 3D printing process entailed using the program Repetier-Host and uploading the catapult design. The individual catapult components were moved closer together to ensure each piece fit on the printer base. The x, y and z axis rotation tool was utilised to have the largest side touching the base. This secures the model during the printing process. Printing options were selected to automatically generate necessary supports and to infill the model at 30%. The 3D printer works by creating thousands of layers and building from bottom up, thus overhanging sections require supports. The printing settings were saved to an SD card and inserted into the 3D printer. The printer was switched on and from the display screen the catapult was selected to begin the 5.5 hour printing process. The base and nozzle temperatures reached 60°C and 210°C respectively, causing the filament to become adhesive.

The completed catapult was used to further students knowledge of Newton’s Second Law of Motion, ‘Force = Mass x Acceleration’ by uploading videos of it working onto the program Tracker. Tracker is a free to download video analysis and modelling software. It manually and automatically tracks objects position, velocity and acceleration overlays. Additionally, it tracks centre of mass, interactive graphical vectors, vector sums, RGB line profiles at any angle and time-dependent RGB regions. Therefore, once the video is uploaded to the software students would be able to track the path the ball travelled to measure the acceleration and consequently calculate the force exerted by the catapult.

Made by Natalie Saltissi, 2019