The questions are on the motion graphs test. Take it under real conditions before reading the mark scheme.
Quick answer: On a distance-time graph the gradient is the speed, and a flat line means the object is stationary. This mark scheme gives the model answers and the marks for the 8 questions of the Physics 9-10 test on motion graphs, from gradient meanings to average speed from points, with the equivalent answers to accept.
Marks are shown for each part. Method marks are given when the working is clear, even if the final value is wrong, so always state which graph feature you used.
Level: Physics grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: IGCSE 1.2
Question 1 Gradient meanings (2 marks)
- The speed of the object.
- The object is stationary (not moving).
Marking: 1 mark each.
Question 2 A short trip (3 marks)
- 15 ÷ 5 = 3.0 m/s.
- The line is horizontal, so the object is stationary at 15 m.
- 15 ÷ 3 = 5.0 m/s back towards the start.
Marking: 1 mark each part.
Question 3 A velocity graph (3 marks)
- a = 10 ÷ 5 = 2.0 m/s².
- Areas: ½ × 5 × 10 = 25 m; 10 × 10 = 100 m; ½ × 5 × 10 = 25 m. Total = 150 m.
Marking: 1 mark for (a); (b) 1 mark for splitting into three areas, 1 mark for 150 m.
Question 4 Units of area (2 marks)
The vertical axis is in m/s and the horizontal axis is in s. The area is height × width, so the units are m/s × s = m, which is a distance.
Marking: 1 mark for the two axis units, 1 mark for the multiplication giving metres.
Question 5 Speeding up then cruising (3 marks)
v = a t = 3.0 × 4.0 = 12 m/s. Distance 1 = ½ × 4.0 × 12 = 24 m. Distance 2 = 12 × 5.0 = 60 m. Total = 24 + 60 = 84 m.
Marking: 1 mark for 12 m/s, 1 mark for 24 m, 1 mark for 84 m.
Question 6 Compare two runners (2 marks)
P: 60 ÷ 10 = 6.0 m/s. Q: 45 ÷ 10 = 4.5 m/s. Runner P is faster because her line has the steeper gradient.
Marking: 1 mark for both speeds, 1 mark for the conclusion.
Question 7 Negative velocity (3 marks)
- a = (−6.0 − 6.0) ÷ 6.0 = −2.0 m/s².
- The velocity passes through zero at 3.0 s.
- The velocity changes sign there, so the glider reverses direction.
Marking: 1 mark each part.
Question 8 Average speed from points (2 marks)
Total distance 180 m in 50 s. Average speed = 180 ÷ 50 = 3.6 m/s.
Marking: 1 mark for 180 m ÷ 50 s, 1 mark for 3.6 m/s.
