Read Motion Graphs: Slope Tells Change, Area Tells Distance
On a speed–time graph, height means speed, slope means acceleration or deceleration, and the area below the graph means distance travelled.
Motion and force questions become simpler when direction, starting condition, time and the acting forces are marked first.
Use the path and the clock together
Mark start, direction and time before reading the graph
Mark a start, direction and time interval first. On a graph, the slope tells how the quantity changes; on a path, distance and displacement may differ.
Read the slope
An upward straight line means constant acceleration; a downward straight line means constant deceleration. A curved line means the acceleration itself may be changing.
Compare areas
For the same time interval, the graph with the larger area underneath represents the greater distance. A horizontal line above zero means distance keeps increasing at constant speed.
OlympIQ exam lens
- ✓Read axes before interpreting a curve.
- ✓Use slope for acceleration language.
- ✓Use area under a speed–time graph for distance.
A speed–time graph below the axis is not valid for ordinary speed; check whether the graph is actually velocity–time before assigning direction.
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