The method and the results are on the motion graphs lab. Do the analysis yourself first, then check 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 answers go with the Physics 9-10 lab on motion graphs: the graph, the calculations, the uncertainties and the conclusion explained, for all 7 analysis questions.
The model answers use the sample table. Your own results will differ a little, but run A should give a straight line and run B an upward-curving line with rising interval speeds.
Level: Physics grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: IGCSE 1.2
Question 1 Shape of the two graphs
Run A: a straight line sloping up through the origin (constant speed). Run B: a curve that gets steeper, so the gradient increases (speeding up).
Question 2 Speed in run A
Gradient = (10.0 − 0) ÷ (13.2 − 0) = 0.7576, so 0.76 m/s.
Question 3 Speeds in run B
Interval times are 4.0, 2.5, 1.8, 1.4 and 1.1 s. Speeds: 2.0 ÷ 4.0 = 0.50 m/s; 2.0 ÷ 2.5 = 0.80 m/s; 2.0 ÷ 1.8 = 1.11 m/s; 2.0 ÷ 1.4 = 1.43 m/s; 2.0 ÷ 1.1 = 1.82 m/s.
Question 4 Interpreting run B
The speeds rise from 0.50 m/s to 1.82 m/s, so the walker is accelerating. The gradient of the distance-time graph grows, which is why the line curves upwards.
Question 5 Estimating acceleration
a = (1.82 − 0.50) ÷ (10.25 − 2.0) = 1.32 ÷ 8.25 = 0.16 m/s².
Question 6 Reliability of the timing
0.2 ÷ 13.2 × 100 = 1.5 %.
Question 7 Improving the lab
1. Use light gates or a phone filming in slow motion to remove reaction time.
2. Use more marks and repeat each run three times, then average the times to cut random error.
