The problems are on the motion graphs worksheet. Try them on your own first, then compare with the answers below.
Quick answer: On a distance-time graph the gradient is the speed, and a flat line means the object is stationary. These worked answers correct the 20 problems of the Physics 9-10 worksheet on motion graphs, from graph facts to overtaking scooter: each solution shows the formula, the substitution and the final answer with its unit.

Each answer shows which feature of the graph is used, the substitution and the final result in bold with its unit. Then, check that you used gradient for rates and area for totals.
Level: Physics grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: IGCSE 1.2
Problem 1 Graph facts
1. speed.
2. Then, acceleration.
3. Next, distance travelled.
4. Then, stationary.
Problem 2 Reading a straight line
1. Moreover, the line passes through 25 m at 10 s.
2. speed = 50 ÷ 20 = 2.5 m/s.
3. d = 2.5 × 16 = 40 m.
Problem 3 Gradient from two points
1. 30 − 6 = 24 m.
2. 8 − 2 = 6 s.
3. gradient = 24 ÷ 6 = 4.0 m/s, the speed.
Problem 4 Describe the sections
1. Next, a: the object is stationary. B: it moves at a high constant speed. Then, C: it moves at a low constant speed.
2. Section B has the steepest gradient, so it is the fastest.
Problem 5 Reading a velocity graph
1. In addition, at 3 s the line is at 6 m/s.
2. a = (12 − 0) ÷ 6 = 2.0 m/s².
3. The line is horizontal, so the bike moves at a constant 12 m/s with zero acceleration.
Problem 6 Rectangle area
1. A horizontal line at 5.0 m/s from 0 to 12 s.
2. area = 5.0 × 12 = 60 m.
3. Also, it represents the distance travelled.
Problem 7 Triangle area
1. In addition, a straight line from the origin sloping up to 9.0 m/s at 6.0 s.
2. a = 9.0 ÷ 6.0 = 1.5 m/s².
3. area = ½ × 6.0 × 9.0 = 27 m.
Problem 8 A walk in stages
1. Section 1: 30 ÷ 20 = 1.5 m/s. Then, section 2: 0 m/s. Section 3: (90 − 30) ÷ (90 − 50) = 60 ÷ 40 = 1.5 m/s.
2. average speed = 90 ÷ 90 = 1.0 m/s.
Problem 9 Out and back
1. 120 ÷ 30 = 4.0 m/s.
2. Also, the return is 120 m in 90 − 50 = 40 s: 3.0 m/s.
3. Distance = 120 + 120 = 240 m. He is back home, so the displacement is 0 m.
Problem 10 Trapezoid journey
1. a = 6.0 ÷ 3.0 = 2.0 m/s².
2. a = (0 − 6.0) ÷ 5.0 = −1.2 m/s².
3. areas: ½ × 3 × 6 = 9 m; 10 × 6 = 60 m; ½ × 5 × 6 = 15 m. Total = 84 m.
Problem 11 From a table to a graph
1. Moreover, the points lie on a straight line through the origin.
2. a = 3 ÷ 2 = 1.5 m/s².
3. area = ½ × 8 × 12 = 48 m.
Problem 12 Two lines compared
1. A: 40 ÷ 10 = 4.0 m/s. B: 25 ÷ 10 = 2.5 m/s.
2. At 20 s A is at 80 m and B at 50 m, so the gap is 30 m.
Problem 13 Slowing to rest
1. Gradient = (0 − 18) ÷ 9.0 = −2.0 m/s².
2. The negative sign shows the velocity is decreasing, so the van decelerates.
3. area = ½ × 9.0 × 18 = 81 m.
Problem 14 Tangent to a curve
1. Then, (11.0 − 3.0) ÷ (3.0 − 1.0) = 8.0 ÷ 2.0 = 4.0 m/s.
2. In addition, it is the speed of the coconut at 2 s.
3. Yes: the curve gets steeper, so the gradient (speed) increases.
Problem 15 From distance to speed steps
1. 0–10 s: 50 ÷ 10 = 5.0 m/s. 10–30 s: 80 ÷ 20 = 4.0 m/s. 30–40 s: 0 m/s.
2. Three flat steps: 5.0 m/s, then 4.0 m/s, then 0 m/s.
3. 130 ÷ 40 = 3.25, so 3.3 m/s.
Problem 16 Robot on a rail
1. Then, stage 1: 4.0 × 5.0 = +20 m. Stage 2: 0 m. So, stage 3: −2.0 × 6.0 = −12 m.
2. displacement = 20 + 0 − 12 = +8 m. Distance = 20 + 12 = 32 m.
3. total time = 14 s. average speed = 32 ÷ 14 = 2.3 m/s. Average velocity = 8 ÷ 14 = 0.57 m/s.
Problem 17 Counting squares
1. Also, one square is 1.0 m/s × 1.0 s = 1.0 m.
2. area ≈ 38 + 14 ÷ 2 = 38 + 7 = 45 squares.
3. Moreover, the distance is about 45 m.
Problem 18 Find the top speed
1. triangle = ½ × 5.0 × V = 2.5 V. Rectangle = 15 × V = 15 V.
2. 2.5 V + 15 V = 17.5 V = 210, so V = 12 m/s.
3. a = 12 ÷ 5.0 = 2.4 m/s².
Problem 19 Spot the graph errors
1. The distance from the start is decreasing, so the object is moving back towards the start. Then, a straight line means constant speed, not slowing.
2. Then, a horizontal line means constant velocity; the object is stationary only if the line is at 0 m/s.
3. Next, a curve that gets flatter (decreasing gradient).
Problem 20 Overtaking scooter
1. In addition, lorry: area of a rectangle = 12 t. Also, scooter: area of a triangle = ½ × t × (2.0 t) = t².
2. t² = 12 t, so t = 12 s (both are then 144 m from the start).
3. v = a t = 2.0 × 12 = 24 m/s, which is twice the lorry’s speed.
