Concept 3 of 3
Speed, Distance & Time: The Triangle
Today's big idea
Speed is the distance covered in one hour, so distance is that same jump repeated.
Speed is to time what a price is to items: the value of exactly one.
How it works
👀 What's going on?
A car covers 80 km in its first hour. In the second hour it covers another 80. Speed is nothing more than that: how far you get in one hour, over and over again.
💡 Here's the trick
Speed is a distance for one unit of time, exactly like a price is a cost for one item. Once you know the size of one hour's jump, distance is those jumps added up. Time is how many jumps it takes to get there. All three questions read off the same picture.
🪄 How to do it
- 1.Find the size of one jump in the picture above, which is the distance covered in a single hour.
- 2.For a distance, count that jump once for every hour.
- 3.For a time, count how many jumps it takes to reach the distance.
✍️ Try it
A train moves at 80 km per hour. How far does it get in 3 hours? And how long would that same train take to cover 400 km?
Three jumps of 80 make 240 km. To reach 400 km you need 400 divided by 80, which is 5 jumps, so 5 hours.
⚠️ Watch out
Match the units before you calculate anything. A speed in km per hour needs a time in hours, so 30 minutes has to become half an hour first. Feeding 30 into the sum instead of 0.5 is what makes an answer come out sixty times too big.
🌟 Why this matters
You do this every time you work out when to leave. A bus at 40 km per hour and a journey of 20 km means half an hour. That is the sum deciding whether you arrive late.
Exam tip: Write the unit next to every number as you work, because a mismatched unit costs more marks here than any slip in the arithmetic.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“A car travels 60 km in 2 hours. Find the speed.”
- 1
Recall the formula
S = D ÷ T. 🚗
- 2
Substitute
S = 60 ÷ 2
- 3
Compute
30 km/h
- 4
Answer ✓
Speed = 30 km/h
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Cover the unknown in the D / (S × T) triangle. What's left is the formula. Convert fractional time to a decimal.
SPEED · ROUND 1 OF 3
Given: Speed 50 km/h, Time 3 h. Find the Distance.
Cover the Distance. Which formula is left?
Quick check
✅ VERIFICATION
A cyclist rides at 12 km per hour. How far does she get in 30 minutes?
⚡ Finish the activity above first to answer.
Keep going!