⚖️
Ratio & Proportion · Foundation & Higher

Speed, distance & time

Speed, distance and time are connected by a formula triangle. Given any two, you can find the third.

🔑

Key facts to remember

  • 1Speed = Distance ÷ Time
  • 2Distance = Speed × Time
  • 3Time = Distance ÷ Speed
  • 4Units must be consistent (e.g. km/h and hours, or m/s and seconds).
  • 5Average speed = total distance ÷ total time (not the mean of two speeds).
📐

Formulas

Speed
S = D/T
Distance
D = S × T
Time
T = D/S
✍️

Worked examples

Example 1

A car travels 180 km at an average speed of 60 km/h. How long does the journey take?

Working

  1. Time = Distance ÷ Speed
  2. T = 180 ÷ 60 = 3 hours
Answer3 hours
Example 2

A runner completes 400 m in 50 seconds. Find their speed in m/s.

Working

  1. Speed = Distance ÷ Time
  2. S = 400 ÷ 50 = 8 m/s
Answer8 m/s
⚠️

Common mistakes

✗Using inconsistent units (e.g. distance in km but time in minutes).
✗Dividing speed by distance instead of distance by speed for time.
✗Calculating average speed as the mean of two speeds rather than total distance ÷ total time.
🎯

Exam tips

✓Use the formula triangle — cover the quantity you want to find.
✓Convert units before calculating: minutes → hours (÷ 60), metres → km (÷ 1000).

Ready to test yourself on Speed, distance & time?

Get AI-marked practice questions on exactly this subtopic.

Practice this topic →
← All topicsDashboard

▶️ Watch on YouTube

Free video lessons

Click a topic to search

▶GCSE speed distance time▶SDT formula triangle GCSE▶average speed GCSE maths▶speed distance time word problems GCSE

Opens YouTube — pick any free GCSE video.