Does twice the speed mean half the journey?
How much time can faster travel actually save?
Start with a concrete question
Plan a synthetic journey with a fixed distance, constant moving speed and fixed delays. This is a mathematical model, not a driving recommendation.
Try the initial inputs, then write a prediction before changing one setting. All calculations run locally on your CPU.
What do you expect?
Predict whether doubling speed halves total time when stops remain unchanged.
Change one thing. Inspect what happens.
- At 12 km, 20 km/h and 6 minutes delay, calculate moving time before reading the trace.
- Double speed to 40. Separate the moving-time change from the total-time change.
- Compare adding 10 km/h at 10 km/h and at 40 km/h. Explain why the savings differ.
Your settingsMechanism
Calculation belowEvidence
Compare outcomes
Compare the current results
Every bar starts at zero and uses the same numeric scale in this chart. The upper bound automatically adjusts to the largest current value (at least 1), so compare the numbers when changing inputs. Units and quantities come from each label; different kinds of quantity are not interchangeable. Displayed values are rounded to at most six significant digits.Follow the calculation
- Time in hours = distance/speed = 12/20 = 0.6.
- Convert to minutes: × 60 = 36. Add 6 minutes of fixed stops.
- At 30 km/h: 60 × 12/30 + 6 = 30 minutes.
Equal increases in speed do not save equal amounts of time. Fixed delays limit the benefit of moving faster.
Captures keep your inputs, prediction and observation. Results are recalculated from those inputs. Resetting inputs keeps your captures and challenge history.
Explain the mechanism
Does twice the speed mean half the journey?
Plan a synthetic journey with a fixed distance, constant moving speed and fixed delays. This is a mathematical model, not a driving recommendation.
Before you change anything
Predict whether doubling speed halves total time when stops remain unchanged.
Follow the mechanism
Speed tells how many kilometres are covered in an hour. Dividing kilometres by kilometres per hour leaves hours.
For 12 km at 20 km/h, 12/20 = 0.6 hours = 36 minutes. Six minutes of stops makes 42 minutes.
At 40 km/h, moving time halves to 18 minutes, but total time is 24 rather than 21. Fixed work remains.
Calculate it yourself
Total minutes = 60 × distance (km) ÷ speed (km/h) + fixed delay (minutes).
Try a counterexample
At 12 km, 20 km/h and 6 minutes delay, calculate moving time before reading the trace.
Double speed to 40. Separate the moving-time change from the total-time change.
Compare adding 10 km/h at 10 km/h and at 40 km/h. Explain why the savings differ.
What this model leaves out
Constant speed ignores acceleration, congestion and changing routes.
The comparison adds 10 km/h mathematically; it does not model safety or legal limits.
Take it further
High school: Draw distance versus time and explain the flat segments.
College: Find the sensitivity of time to speed and interpret its units.
Working professionals: Apply fixed versus variable time to a workflow before proposing an optimization.
Try a fresh case
A different journey covers 15 km at 30 km/h with 8 minutes of stops. How many minutes in total?
This is a public practice check. Retries support learning; matching a number does not certify independent proficiency.
Take the investigation further
Choose any extension. These are project prompts for you to carry out; they are not automatically assessed.
School investigation
Draw distance versus time and explain the flat segments.
College investigation
Find the sensitivity of time to speed and interpret its units.
Workplace investigation
Apply fixed versus variable time to a workflow before proposing an optimization.
Keep the evidence, choose your next step
Completion records your own decision that you have worked through this investigation. Practice checks and independent project evidence are separate.