The questions are on the speed and velocity test. Take it under real conditions before reading the mark scheme.
Quick answer: Speed is distance divided by time, while velocity is displacement divided by time and includes direction. This mark scheme gives the model answers and the marks for the 8 questions of the Physics 9-10 test on speed and velocity, from scalars and vectors to average speed of a run, with the equivalent answers to accept.
Marks are shown for each part. Method marks are awarded even when the final value is wrong, provided your working is clear, so always show the formula and the substitution.
Level: Physics grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: IGCSE 1.2, HS-PS2-1
Question 1 Scalars and vectors (2 marks)
- Displacement is a vector.
- Speed is a scalar.
Marking: 1 mark each.
Question 2 Jogger’s speed (3 marks)
(a) 1.8 km = 1800 m and 12 min = 720 s.
(b) v = 1800 ÷ 720 = 2.5 m/s.
Marking: 1 mark for both conversions, 1 mark for distance ÷ time, 1 mark for 2.5 m/s.
Question 3 Acceleration of a bike (3 marks)
a = (v − u) ÷ t = (24 − 6.0) ÷ 4.5 = 18 ÷ 4.5 = 4.0 m/s².
Marking: 1 mark for the formula, 1 mark for the substitution, 1 mark for the answer with the unit.
Question 4 Across a field (3 marks)
(a) 40 + 30 = 70 m.
(b) d² = 40² + 30² = 1600 + 900 = 2500, so d = 50 m.
Marking: 1 mark for (a); 1 mark for Pythagoras, 1 mark for 50 m.
Question 5 Bus braking (2 marks)
a = (0 − 15) ÷ 6.0 = −2.5 m/s². The negative sign means the bus is slowing down (decelerating).
Marking: 1 mark for the value, 1 mark for the meaning of the sign.
Question 6 Acceleration at steady speed (2 marks)
Acceleration is a change in velocity. The speed is constant but the direction keeps changing, so the velocity changes and the car is accelerating.
Marking: 1 mark for velocity includes direction, 1 mark for direction changes.
Question 7 Final velocity (3 marks)
v = u + a t = 2.0 + 0.50 × 12 = 2.0 + 6.0 = 8.0 m/s.
Marking: 1 mark for the equation, 1 mark for the substitution, 1 mark for 8.0 m/s.
Question 8 Average speed of a run (2 marks)
Total distance 300 m; total time 20 + 30 = 50 s. Speed = 300 ÷ 50 = 6.0 m/s.
Marking: 1 mark for total distance and time, 1 mark for the answer.
