Maths · Algebra and graphs. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
Graphs can show real situations such as a journey, a cost or a conversion between units. Always read the labels and the scale on each axis before you read any value.
On a distance–time graph the gradient is the speed. A steeper line means faster, a horizontal line means the object is not moving, and a line going back down means it is returning.
On a speed–time graph the gradient is the acceleration. A line going down shows deceleration and a horizontal line shows constant speed. The area under the graph is the distance travelled. Split the area into triangles, rectangles and trapeziums to find it.
Students read the height of a speed–time graph as the distance. The height is the speed; the distance is the area under the line. Check also that the time is in hours if the speed is in km/h.
Answer: Acceleration = 2 m/s², distance = 110 m
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