Graphs of Motion
Gradient
How steep a line is; the rate of change of the vertical axis with respect to the horizontal.
| English | Gradient |
|---|---|
| Bahasa Melayu | Kecerunan |
| 中文 | 斜率 |
How it is used
On a distance–time graph, a line rises from (0 s, 0 m) to (8 s, 240 m). The gradient is (240 − 0) ÷ (8 − 0) = 30, so the speed is 30 m/s.
Where it shows up in SPM
Across Graphs of Motion, Linear Equations and Straight Lines (Form 4). In motion questions the gradient carries a physical meaning: on a distance–time graph it is speed, on a speed–time graph it is acceleration.
Both papers test it; Paper 2 usually asks you to state units too.
Don't confuse it with
Open the chapter: Graphs of Motion →
Frequently asked questions
What does a negative gradient tell me in a motion graph?
On a distance–time graph a negative gradient means the object is moving back toward the start. On a speed–time graph it means the speed is falling, i.e.
deceleration. The number's size still tells you how fast the change is happening.
Do I always read two points off the graph to find gradient?
Yes, pick two points that lie exactly on grid crossings so your reading is accurate, then use gradient = (y₂ − y₁) ÷ (x₂ − x₁). Choosing points far apart reduces reading error.
Always write the units that match the axes.