Distance-time graphs
Gradient = speed. Horizontal = stationary. Steeper = faster.
Axes: time on , distance on .
Reading:
- Steeper gradient = faster speed.
- Horizontal line = stationary (not moving).
- Negative gradient = returning.
Speed = gradient = .
Example. Travel km in hours.
- Speed = km/h.
Multi-stage journeys. Each section has its own gradient = its own speed.
Worked qualitative. A distance-time graph shows:
- h: rises to km.
- h: horizontal at km.
- h: rises to km.
What's the journey?
- First h: km/h.
- Middle h: stopped (rest).
- Last h: km/h.
- Total: km in h, average km/h.
Edexcel tip. Always state UNITS with speed (km/h or m/s). Mark schemes credit unit consistency.
- Time x, distance y.
- Gradient = speed.
- Horizontal = stationary.
- Average speed = total distance / total time.