Graphs of Motion · 7.1.2
Interpreting distance-time graphs
Students read a given distance-time graph to describe the motion it represents, identifying periods of constant speed, rest, or a return journey, and use the gradient of each segment to determine the speed during that part of the journey.
The official learning standard (7.1.2)
“Interpret distance-time graphs and describe the motion based on the graphs. Description of motion needs to involve distance, time and speed.”
What it means
Students read a given distance-time graph to describe the motion it represents, identifying periods of constant speed, rest, or a return journey, and use the gradient of each segment to determine the speed during that part of the journey.
How it is examined
Common in both papers: Paper 1 objective questions ask for the speed or distance at a stated time from a graph, while Paper 2 requires a fuller description of the motion across the whole journey, including calculating speed from the gradients of different segments.
Worked example
A distance-time graph shows a car travelling 60 km in 2 hours, staying at 60 km for the next hour, then returning 60 km over the following 1.5 hours. Describe the motion and find the speed for each stage.
- Stage 1 (0-2 h): distance covered = 60 km, speed = 60 ÷ 2 = 30 km/h (moving away from the start).
- Stage 2 (2-3 h): distance stays at 60 km, speed = 0 km/h (the car is stationary/resting).
- Stage 3 (3-4.5 h): distance decreases from 60 km to 0 km over 1.5 h, speed = 60 ÷ 1.5 = 40 km/h (returning to the start).
Source:DSKP KSSM Mathematics Form 4 and 5 (Versi English)
Frequently asked questions
How do I find the speed from the graph?
Speed equals the gradient of the line segment, calculated as the change in distance divided by the change in time for that particular section of the graph.
What does a steeper line mean?
A steeper line indicates a greater gradient, meaning the object is travelling at a higher speed during that section of the journey.
How can I tell if the object is returning to the start?
The distance value decreases as time increases, shown by a line sloping downward back toward the time axis on the graph.