Describing Motion
运动的描述
The particle model and choice of reference frame, scalars versus vectors, and the definitions and calculation of distance, displacement, speed and velocity.
Formulas
Average speed
DefinitionApplies when：s is the path length and t the elapsed time; average speed is a scalar
How the real exam tests it
Questions from real CSCA papers that test this concept. Work each one out before you open the answer.
- CSCA Physics December 2025 Past PaperWhich of the following physical quantities is not a vector? ()
- A．Magnetic flux density
- B．Momentum
- C．Electric field strength
- D．Potential energy
See it in the full CSCA Physics December 2025 Past PaperShow answer & solution
Answer: D
1 A vector has magnitude and direction; potential energy is a scalar quantity. - CSCA Physics March 2026 Past PaperWhich of the following physical quantities is a scalar?
- A．Velocity
- B．Acceleration
- C．Displacement
- D．Distance
Take the full CSCA Physics March 2026 Past Paper — timed & gradedShow answer & solution
Answer: D
Scalars have magnitude only; vectors have both magnitude and direction. A. Velocity: has direction, vector. B. Acceleration: has direction, vector. C. Displacement: directed line segment, vector. D. Distance: total path length, magnitude only, scalar. Answer: D. - CSCA Physics April 2026 Past PaperWhile sitting in a uniformly moving train, you see the trees outside the window moving backward. The reference frame you are using is
- A．the Sun
- B．the trees
- C．the ground
- D．the train
Take the full CSCA Physics April 2026 Past Paper — timed & gradedShow answer & solution
Answer: D
Observing the trees as 'moving backward' implies your frame is moving forward relative to the trees, i.e., the train.
Real-exam evidence
Recorded past-paper appearances are listed below; online verification is labelled separately.
- CSCA Physics April 2026 Past Paper3 questionsreading page not yet public
- CSCA Physics March 2026 Past Paper3 questionsreading page not yet public
- CSCA Physics January 2026 Past Paper3 questionsreading page not yet public
- CSCA Physics December 2025 Past Paper4 questionsView question 1 and answer free (full paper)View question 13 and answer free (full paper)View question 14 and answer free (full paper)View question 17 and answer free (full paper)
21 questions across 6 mock papers — our own papers, so a coverage signal rather than real-exam evidence
15 related practice questions availablePractise free: Kinematics
Sitting evidence comes from the CSCA past papers on record; questions whose original paper is missing are excluded, and sprint papers are deliberately not counted.