HSC Physics — Module 1
Equations of Motion — Flashcards & Quiz
The HSC Physics Module 1 equations of motion (SUVAT) let you solve uniformly accelerated motion problems given any three of the five variables: displacement (s), initial velocity (u), final velocity (v), acceleration (a) and time (t). The standard set is v = u + at, s = ut + ½ at², v² = u² + 2as, s = ½(u+v)t. You must choose the right equation based on what you know and what you need.
Key Points
- The five SUVAT equations apply only to UNIFORMLY accelerated motion (constant a). Always check this assumption.
- Choose the equation that uses the three variables you know and gives you the one you want — most problems fit one of v = u + at, s = ut + ½at², or v² = u² + 2as.
- Sign convention: choose a positive direction (usually up or forward) and apply it consistently to displacement, velocity, and acceleration.
- Free fall under gravity uses a = -9.8 m s⁻² (pointing down); if up is positive, initial velocity upward is positive and g is negative.
- Average velocity for uniformly accelerated motion: v_avg = (u + v) / 2 — useful when you know start and end velocities.
- Exam skill: read the question twice, list u/v/a/s/t knowns and unknowns, pick the equation that fits, then solve symbolically before substituting numbers.
Common Mistakes to Avoid
- Applying SUVAT to non-uniform acceleration — it only works when a is constant.
- Mixing up initial (u) and final (v) velocity in the equations.
- Using the wrong equation — always pick the one that uses the three knowns and gives you the unknown.
- Forgetting signs for direction — up is usually positive, down is negative with g = -9.8 m/s².
- Not converting units consistently — km/h and m/s give different numerical answers.
Exam Strategy
HSC Module 1 SUVAT questions give you a motion scenario and ask you to find one unknown. Method: (1) list knowns (u, v, a, s, t), (2) identify the unknown, (3) choose the SUVAT equation that links them, (4) solve symbolically before substituting numbers, (5) check units and sign.
Sample Flashcards
Q1: State the four equations of uniform acceleration (SUVAT).
v = u + at; s = ut + ½at²; v² = u² + 2as; s = ½(u + v)t. Where s = displacement, u = initial velocity, v = final velocity, a = acceleration, t = time. These apply ONLY when acceleration is constant.
Q2: How do you choose which equation of motion to use?
Identify the three known quantities and the unknown from s, u, v, a, t. Choose the equation that contains all three knowns and the unknown: v = u + at (no s), s = ut + ½at² (no v), v² = u² + 2as (no t), s = ½(u+v)t (no a).
Sample Quiz Questions
Q1: The SUVAT equations can only be used when acceleration is constant.
Answer: TRUE
The equations v = u + at, s = ut + ½at², v² = u² + 2as, s = ½(u+v)t are derived assuming constant (uniform) acceleration. For varying acceleration, calculus-based methods are needed.
Revision Tip
SUVAT equations are formula-choice exercises — drill Revizi flashcards with problems requiring each of the five equations so you learn which one to pick.
Related Concepts
Last updated: March 2026 · 2 flashcards · 1 quiz questions