Each step up is roughly 10× faster. Human intuition covers only the first few rows.
Snail
0.05 km/h
Human walk
5 km/h
Cycling
15–25 km/h
City car / sprint
~30–50 km/h
Motorway car
~120 km/h
High-speed train (TGV)
~300 km/h
Commercial plane
~900 km/h
Concorde (retired)
~2,170 km/h — Mach 2
SR-71 spy plane
~3,540 km/h — Mach 3.2
Speed of sound (air)
1,235 km/h — Mach 1
ISS / orbital speed
~28,000 km/h
Speed of light
1,080,000,000 km/h
Light is 1,200,000× faster than a plane. The ISS orbits Earth every 92 minutes — 16 sunrises per day.
Part B · the key speed anchors you'll use every day
Walking
5 km/h
1 km = 12 min walk. 10 min = ~800 m. The foundation of all human-scale distance sense.
Cycling
~20 km/h
4× walking. 1 km = 3 min. 10 km commute = 30 min by bike.
Motorway driving
~120 km/h
2 km per minute. 100 km = ~50 min. 1 hr = ~120 km.
Commercial flight
~900 km/h
15 km per minute. 1,000 km ≈ 1 hr. The Module 3 anchor in action.
The travel time formula — works for any journey
Time = Distance ÷ Speed. Always in the same units.
300 km by car at 100 km/h = 3 hours.
300 km by plane at 900 km/h = 20 minutes (plus airport time — realistically 3 hrs total).
300 km by TGV at 300 km/h = 1 hour — often faster door-to-door than flying.
Part C · interactive speed & distance calculator
How long does a journey take? Pick a speed and enter a distance.
Part D · how long does it actually take? duration anchors
Real-world task durations — most people underestimate these
Boiling water (1L)
~4 min
Cooking pasta
8–12 min
Roasting a chicken (1.5kg)
~90 min
Appendix surgery
30–60 min
Hip replacement
1–2 hours
Open-heart surgery
4–6 hours
Building a house
6–18 months
Building a skyscraper
3–5 years
Building a nuclear plant
10–20 years
Writing a PhD thesis
3–5 years
Becoming a surgeon
12–15 years training
Part E · human body speeds — things happening inside you right now
Nerve signal speed
~70 m/s
252 km/h. Pain signals are slower (~1 m/s). That's why you feel a stubbed toe slightly after you see it happen.
Blood circulation (full loop)
~60 seconds
Blood travels ~5 km of vessels to complete one full circuit of your body every ~1 minute.
Heart beats per minute
~60–100 bpm
~100,000 beats per day. ~3 billion beats in a lifetime. It never stops for a rest longer than 1 second.
Blink duration
~150–400 ms
You blink 15–20 times per minute. Total "blind time" per day: ~30 minutes. You never notice.
Part F · the speed of light — putting the universe in perspective
Light travels 300,000 km per second. How far in each timeframe?
1 nanosecond
30 cm — a ruler
1 blink (200ms)
60,000 km
1 second
300,000 km — Earth→Moon
1 minute
18M km
8 minutes
150M km — Earth to Sun
4.2 years
nearest star (Proxima Centauri)
When you look at the Sun, you're seeing it as it was 8 minutes ago. When you look at Proxima Centauri, you're seeing 4.2 years into the past. The night sky is a time machine — the further you look, the older the light.
Part G · anchor numbers to memorize
5 km/h
Human walking speed
1 km = 12 min · the foundation of all distance intuition
120 km/h
Motorway car — 2 km per minute
100 km = ~50 min driving
300 km/h
High-speed train (TGV, Shinkansen)
Often faster than flying for <500 km city-centre to city-centre
900 km/h
Commercial aircraft
1,000 km ≈ 1 hour — the module 3 rule
1,235 km/h
Speed of sound (Mach 1) at sea level
Thunder arrives ~3 sec after lightning per km of distance
300,000 km/s
Speed of light
Earth to Moon in 1.3 sec · Earth to Sun in 8 min
Part H · test yourself
1. You hear thunder 6 seconds after a lightning flash. How far away is the storm?
About 2 km. Sound travels ~340 m/s (1.2 km per 3.5 seconds). The rule of thumb: 3 seconds of delay ≈ 1 km. So 6 seconds ≈ 2 km. Light from the flash arrives almost instantly (it's less than a millisecond delay at 2 km), so the gap is purely sound travel time. At 6 seconds, the storm is close — seek shelter.
2. Paris to Lyon is about 460 km. Which is faster door-to-door: TGV or plane?
The TGV — easily. The train takes about 2 hours at ~300 km/h, city-centre to city-centre. A flight takes ~1 hour in the air, but add 45 min check-in, 30 min to/from each airport, and 20 min baggage = ~3.5–4 hours total. For any journey under ~600 km between well-connected cities, high-speed rail is almost always faster door-to-door than flying.
3. The ISS orbits at 28,000 km/h. How long does one full orbit of Earth take?
About 92 minutes. Earth's circumference at orbital altitude (~400 km up) is roughly 42,000 km. 42,000 ÷ 28,000 ≈ 1.5 hours = 90 minutes. This means ISS astronauts see 16 sunrises and sunsets every single day — one every 45 minutes.
4. A surgeon says your operation will take "about 3 to 4 hours." Is that unusual, or normal for major surgery?
Completely normal for major surgery. Appendix removal: 30–60 min (minor). Hip replacement: 1–2 hours. Knee replacement: 1–2 hours. Open-heart surgery: 4–6 hours. Liver transplant: 6–12 hours. A 3–4 hour estimate puts you in the "significant but routine" category — complex enough to require careful work, but not an unusually long procedure. Add recovery room time and you're typically looking at waking up 1–2 hours after the stated surgery duration.
5. You're driving at 90 km/h and need to stop suddenly. Roughly how far does the car travel while you react and brake?
About 55–65 metres total. At 90 km/h you're travelling 25 metres per second. Human reaction time is ~0.7–1 second, covering ~18–25 metres before you even touch the brakes. Then braking distance at 90 km/h on dry road is roughly 40 metres. Total: ~55–65 m. On wet roads, add 50%. This is why motorway tailgating is so dangerous — at 120 km/h, the total stopping distance exceeds 90 metres, longer than a football pitch.