Year 9 STEM Exam Study Notes: CAD, Technical Drawing, Design Process, and Medical Technology

Comprehensive practice flashcards in question-and-answer format reviewing Year 9 STEM topics: CAD modeling functions, Fusion 360 operations, AS 1100 technical drawing standards, the engineering design process, and medical device design considerations.

How does the transcript define each discipline within the STEM acronym?

Science is understanding the natural world; Technology comprises tools and systems made to solve problems; Engineering is designing and building solutions using science, maths, and technology; Mathematics involves measurement, calculation, geometry, and data used to design and test.

In STEM design fundamentals, what is the difference between criteria and constraints?

Criteria are what the solution must achieve (e.g. holds $2\,\text{kg}$, costs under $\$10$), whereas constraints are limits placed on the design (such as time, budget, materials, size, safety, and skills).

What is a trade-off in engineering design?

A trade-off is giving up one quality in order to gain another (for example, making a product stronger but heavier).

How are hardness and toughness distinguished as material properties?

Hardness is the property of resisting scratching or denting, while toughness is the ability to absorb impact without fracturing.

Why is triangulation used in frames such as trusses and bridges?

Triangles are rigid, meaning triangulation strengthens structural frames against applied loads.

What is tolerance in CAD, and what clearance is typically recommended for 3D printed joins?

Tolerance is the allowed variation in dimensions so that parts fit together properly. A clearance of $0.2\text{--}0.5\,\text{mm}$ is added for 3D printed joins.

What is an isometric view in CAD and technical drawing?

An isometric view is a 3D-looking view drawn with axes at $30^\circ$ to the horizontal, with all edges drawn at the same scale and vertical lines remaining vertical.

What is the primary function of Extrude in CAD, and what is an example of its use?

Extrude pushes or pulls a 2D sketch into a 3D solid (either adding or cutting material), such as turning a circle into a cylinder.

What is the function of Revolve in CAD, and what types of shapes does it produce?

Revolve spins a 2D profile around an axis to create a round 3D shape, such as a vase, bottle, or wheel.

How do Sweep and Loft differ in CAD modeling?

Sweep moves a single profile along a straight or curved path (e.g. pipes, handles), whereas Loft blends smoothly between two or more different profiles (e.g. from a square to a circle, funnels, bottle necks).

What is the physical difference between a fillet and a chamfer?

A fillet rounds an edge or corner with a curved round (specified by radius), whereas a chamfer cuts a flat, straight angled bevel on an edge.

What do blue lines and black lines represent in a Fusion 360 sketch?

Blue lines indicate an under-constrained sketch that can still move, while black lines indicate a fully constrained sketch locked in place by dimensions and constraints.

How do Extrude ($E$) and Press/Pull ($Q$) differ in Fusion 360?

Press/Pull ($Q$) is quick, automatic, and changes behavior based on whether a face or profile is selected. Extrude ($E$) provides explicit control over Boolean operations: New Body, Join, Cut, or Intersect.

What are the three coordinate axes and their corresponding colors in Fusion 360?

The three axes are $X$ (red), $Y$ (green), and $Z$ (blue).

How are pan and orbit performed in Fusion 360 using a Mac trackpad?

Pan is performed with a two finger click and press to move the view without rotating. Orbit is performed with a two finger click and press to rotate the view around the model.

In CAD, what is the distinction between a Component and an Assembly?

A Component is an independent container for design elements (sketches, bodies, joints, history) representing one part. An Assembly is a collection of components connected by joints to interact and move together.

How do ribs and webs differ as structural support features in CAD?

Ribs are small, thin strengthening walls (such as under a 3D-printed bracket), while webs are larger flat plates that connect and reinforce surfaces across large sections to prevent bending (such as in a bridge beam).

Which file formats are used for laser cutting and standard 3D printing, respectively?

DXF is used for laser cutting (stores flat 2D geometry), while STL is standard for 3D printing (stores surface geometry as a mesh of triangles).

What advantages does the 3MF file format have over the STL format for 3D printing?

While STL only stores surface geometry as a mesh without color or texture, 3MF stores more detail including color, materials, and complete model data in a single file.

What is the Australian standard for technical drawing, and what do AS 1100.101 and AS 1100.201 cover?

The standard is AS 1100. AS 1100.101 covers general principles of technical drawing, and AS 1100.201 covers mechanical engineering drawing.

In AS 1100, what are the line appearances and uses for continuous thick, dashed thin, and chain thin lines?

Continuous thick (solid, dark) is used for visible outlines and edges; dashed thin (short dashes) is used for hidden detail; chain thin (dash-dot) is used for centre lines and axes of symmetry.

What projection method is standard in Australian AS 1100 drawings, and how are the views positioned?

Third angle projection is standard. The front view is in the centre, the top (plan) view is placed directly above the front view, and the right-hand view is placed directly to the right of the front view.

What are two key rules for dimensioning under AS 1100?

Dimensions are given in millimetres without writing the '$\text{mm}$' symbol, numbers are written above the dimension line readable from the bottom or right, smaller dimensions are placed closer to the object, and diameters use $\varnothing$ while radii use $R$.

If an AS 1100 drawing has a scale of $1:2$ and a feature measures $30\,\text{mm}$ on paper, what dimension number is written on the drawing?

The number written is $60$, because technical drawing dimensions always state the real-world size regardless of drawing scale.

What is the difference between cavalier oblique and cabinet oblique drawings?

In oblique drawings, front faces are drawn true shape with receding lines at $45^\circ$. Cavalier draws depth at full scale, whereas cabinet draws depth at half scale to look more natural.

What are the 8 stages of the class version of the engineering design process in order?

1. Define the problem, 2. Identify constraints and criteria, 3. Brainstorm, 4. Select, 5. Prototype, 6. Test, 7. Iterate, 8. Communicate.

What memory trick is given to recall the 8 stages of the engineering design process?

'Don't Ignore Big Stupid Problems, Test, Improve, Communicate' (standing for Define, Identify, Brainstorm, Select, Prototype, Test, Iterate, Communicate).

What are the three components of a PMI chart, and what does each evaluate?

Plus: what the product does well; Minus: drawbacks of the product; Interesting: fascinating aspects, curiosities, questions, or ideas that lead into brainstorming.

What does each letter in the SCAMPER design method stand for?

S = Substitute, C = Combine, A = Adapt, M = Modify, P = Put to another use, E = Eliminate, R = Rearrange / Recycle.

What are the three mandatory parts required when answering a SCAMPER question?

1. Name the technique. 2. State the specific change to the design. 3. Link the change to customer feedback, a need, or a constraint it solves.

What is biocompatibility in medical technology design, and which materials are examples of biocompatible options?

Biocompatibility means materials must not cause a toxic or harmful immune reaction in the patient's body; examples include titanium and medical-grade silicone.

What regulatory agency governs medical devices in Australia?

The Therapeutic Goods Administration (TGA).