Week 3 Study Guide — Motion in 2D and Relative Motion

Directly supported by notes

These topics are explicitly covered in the lecture slides, the handwritten notes, and Tutorial 3:

Topic	Direct source coverage
Continuous improvement framing	Slides 3–7 (marginal gains, PDCA, Model–Visualise–Solve–Assess)
1D kinematics review	Slide 9 (definitions, calculus links), slide 10 (four SUVAT equations)
2D vectors	Slide 11 (polar/Cartesian, quadrant correction)
2D kinematics framework	Slides 12–14 (orthogonal-plane decomposition, workflow)
Worked Example 1 — rifle shot	Slide 15 + handwritten notes pp. 1–2
Worked Example 2 — cliff projectile	Slide 16 + handwritten notes pp. 3–5
Relative velocity in 2D	Slides 17–18 (subscript convention, per-plane application)
Worked Example 3 — plane in crosswind	Slide 19 + handwritten notes p. 6
Tutorial Exercises 1–4	Tutorial 3.pdf + Tutorial 3_Solutions.pdf
Assessment pointer	Slide 21 (Portfolio 2 assessed in Workshop class)

You should be able to:

1. Apply the four SUVAT equations correctly per plane in a 2D problem.
2. Convert vectors between polar and Cartesian forms, including the quadrant correction.
3. Set up a projectile problem with explicit axes and sign conventions.
4. Apply ${\vec{v}}_{OG}={\vec{v}}_{OM}+{\vec{v}}_{MG}$ component-wise.
5. Sanity-check answers via units, signs, and order of magnitude (the “Assess” step).

Strongly inferred

These are likely covered in the lecture or expected as background, even where the slides do not state them word-for-word:

• The four SUVAT equations are valid only when $a$ is constant; for variable acceleration, integrate $a(t)$ and $v(t)$.
• “Speed” is the magnitude of $\vec{v}$; “velocity” requires direction (the handwritten notes p. 2 calls this out).
• At the peak of a projectile’s trajectory (with $+y$ up), $v_y=0$ but $v_x=u_x$ still — symmetry of the parabolic trajectory.
• Range formula $R=u^2\sin (2\theta )/g$ for flat-ground projectile motion (derivable from SUVAT, not necessarily stated in lecture).
• Air resistance is always neglected in this lecture’s examples.
• Conversion: km/h ÷ 3.6 = m/s (used implicitly in Tutorial Exercises 2 and 4).

Possible lecture content (not pinned to a slide)

May feature in the lecture but not visible in extracted slides or tutorial:

• Derivation of $v^2=u^2+2as$ from the other SUVAT equations.
• Vector addition by tip-to-tail diagrams (likely shown on a slide as a visual aid).
• A discussion of why the projectile trajectory is a parabola: $y$ as a quadratic function of $x$.
• Demonstration of the symmetry of projectile motion (time-up = time-down on level ground).

Gaps requiring official source check

• The lecture deck has slides 1–22 (per the lecture-summary), but slides 1–8, 17, 20, 22 are not described in detail in the reconstructed summary. Worth re-reading.
• Whether the assessment includes problems with non-constant acceleration (e.g. drag-dependent motion). If so, calculus-based integration would be needed.
• Whether Portfolio 2 specifically tests relative motion, or only projectile + 2D kinematics.

Worked examples (links)

Two notes work this material at different depths:

• Cheatsheet — every formula, table, and recipe on one page. Includes the full quiz (mixed difficulty, reshuffles every visit).
• In-depth note — why orthogonal decomposition works, why the SUVAT equations exist, the ${\tan }^{-1}$ quadrant pitfall, and full worked examples for the rifle, the cliff projectile, the crosswind plane, and the Furious 7 car jump.
• Lecture summary — the literal lecture reconstruction with every formula and worked example, plus outline solutions to all four tutorial exercises.

Common mistakes

• Sign of $g$. If $+y$ is up, $a_y=-9.81$. If $+y$ is down, $a_y=+9.81$. Choose once and be consistent.
• ${\tan }^{-1}$ quadrant. Calculator returns $(-90°,90°)$. Add $180°$ for quadrants 2 and 3.
• Mixing planes too early. $x$ and $y$ equations are independent. Only $t$ links them.
• Speed vs velocity. Speed is $|\vec{v}|$; velocity requires direction.
• Using SUVAT when $a$ varies. Only valid for constant $a$.
• Unit consistency. Convert km/h to m/s, minutes to seconds, before plugging into $g=9.81$ m/s${}^2$.
• Skipping the Assess step. Order-of-magnitude and sign checks catch most errors.

Practice questions

From Tutorial 3 (recommended order):

• Exercise 1 — Displacement from velocity-time graphs. Builds intuition that area under $v$-$t$ = displacement.
• Exercise 2 — Furious 7 car jump (horizontal launch, drop, find horizontal distance). Classic projectile starter.
• Exercise 3 — Slingshot to climbers (angled launch, given horizontal + vertical targets, find launch speed). The trickiest of the four — two equations, two unknowns.
• Exercise 4 — Plane in wind (vector subtraction to find wind velocity). The relative-motion finale.

Also recommended:

• Mastering Physics, Motion in 2D problem set.
• Wolfson, Essential University Physics, Chapter 2.

Assessment relevance

• Portfolio 2 is assessed in the Workshop class for this week (slide 21). Study Week 2 eContent + Lecture 3 + Tutorial 3 together.
• 2D kinematics and projectile motion appear in essentially every EGD102 exam paper.
• Relative velocity is the standard “trick” topic — at least one short question per paper.

Confidence report

• Directly supported: all six topic areas listed above and their associated formulas, plus Examples 1–3 from the slides and handwritten notes.
• Inferred: symmetry shortcuts (peak time, range formula), unit conversion habits, the framing of “speed vs velocity.”
• Gap: unparsed lecture content on slides 1–8, 17, 20, 22; full scope of Portfolio 2 task list.

Source files used

• EGD102-Physics/Lecture3_CTP1.pdf (lecture deck, CTP1 2026; slides 1–22).
• EGD102-Physics/EGD102 - Lecture3 - Notes.pdf (handwritten worked solutions for Examples 1–3, pp. 1–6).
• EGD102-Physics/Tutorial 3.pdf (Exercises 1–4).
• EGD102-Physics/Tutorial 3_Solutions.pdf (full solutions, pp. 1–5).
• Textbook reference: Wolfson, R. 2020. Essential University Physics, Vol. 1, 4th ed. SI Units, Chapter 2.