Speed, distance, and time are related by a simple formula. GCSE questions often involve calculating one quantity given the other two, working with different units, and finding average speed.
Core Formula
Units
- km/h, m/s, mph
- km/h → m/s: ÷ 3.6 (or × )
- m/s → km/h: × 3.6
Average Speed
Worked Example: Example 1
A car travels 150 km in 2.5 hours. Speed = km/h.
Worked Example: Example 2
A cyclist rides at 12 km/h for 45 minutes. Distance = km.
Worked Example: Example 3
Jan drives 100 km at 80 km/h, then 60 km at 40 km/h.
Total distance = 160 km. Total time = hours.
Average speed = km/h.
Practice Problems
- Distance 240 km, time 3 hours. Find speed.
- Speed 15 m/s for 2 minutes. Find distance.
- Convert 90 km/h to m/s.
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Key Takeaways
, , .
Average speed uses total distance and total time.
Watch units — convert minutes to hours if using km/h.
