Speed, time and distance
How long does the trip take? How fast did they drive? If you know two of speed, time and distance, you can find the third.
The explanation is shown. Quick: two numbers in, the answer out. Advanced: what the answer becomes if the speed or the time changes.
Your numbers
Answer
Time
1 h 30 min
In hours
1.5h
In minutes
90min
How to work it out
- 1t = s / v = 120 km / 80 km/h = 1.5 h
- 20.5 h · 60 = 30 min
The formula
s = v · t
Distance = speed times time.
v = s / t · t = s / v
Keep the units consistent: km/h goes with km and hours. 30 minutes is 0.5 hours — not 0.3.
In depth: more numbers and “what if”
What if the speed is different?
| Speed | Time |
|---|---|
| 60 km/h | 2 h 0 min |
| 70 km/h | 1 h 43 min |
| 80 km/h | 1 h 30 min |
| 90 km/h | 1 h 20 min |
| 100 km/h | 1 h 12 min |
A speed of 80 km/h is 22.22 m/s, and it takes 0.75 min to travel 1 km.