SpeedTime Graphs

Speedtime graphs represent how the speed of an object changes over a period of time.

The horizontal axis (‘x’ axis) represents time, normally in seconds (s) or minutes (m), while the vertical axis (‘y’ axis) represents speed, usually in metres per second (m/s) or kilometres per hour (km/h).

If the graph line is horizontal (parallel to the time axis), this means the speed is constant. The object is moving at a steady speed.

If the graph line rises, the speed is increasing. This indicates acceleration.

If the graph line falls, the speed is decreasing, indicating deceleration or slowing down.

The steeper the line on a speedtime graph, the greater the acceleration or deceleration.

The gradient of a speedtime graph represents acceleration or deceleration. This can be calculated using the formula: “change in speed ÷ change in time”.

Area under the graph line represents the total distance travelled.

If the graph line resets to zero, this indicates that the object has stopped.

By segmenting the graph and calculating individual areas, we can determine the distance travelled during various stages of motion.

Remember that speed cannot be negative in a speedtime graph. If dealing with different directions, use separate graphs.

Ensure to check units consistently in questions involving converting units of speed or time.

Exercise caution with graphs that contain curves as this represents changing acceleration.

Keep practicing drawing and interpreting various speedtime graphs to strengthen your understanding and to be prepared for different scenarios in assessments.