physics
did you know speeding doesn’t save as much time as you think?
on a 100-mile trip, going 80 instead of 60 saves about 25 minutes. on a 10-mile trip it saves about 2.
driving 100 miles at 80 instead of 60 mph saves 25 minutes
the idea
time saved shrinks as speed rises. going from 30 to 40 mph on a short trip saves you a couple of minutes — the same jump that feels like it should matter far more.
how it works
the faster you already are, the less each extra mph buys you. time is distance divided by speed, and division flattens out.
go deeper
the minutes don’t add up the way you feel
100 miles at 60 mph takes 100 minutes. at 80 mph it takes 75. twenty-five minutes saved over nearly two hours of driving.
on a 10-mile trip to the shops, the same 20 mph difference saves about two and a half minutes. two and a half.
time is distance divided by speed
the faster you already are, the less each extra mph buys you. time is distance divided by speed, and division flattens out.
from 20 to 30 mph, a 10-mile trip drops from 30 to 20 minutes — ten whole minutes. from 60 to 70 mph, the same trip saves barely one.
time = distance ÷ speed
a curve, not a line
plot time against speed and you get a 1/x curve: steep at low speeds, almost flat at high ones.
each additional mph saves less than the one before. mathematicians call this diminishing returns, and your schedule calls it disappointing.
minutes saved = 60 × d × (1 ÷ v₁ − 1 ÷ v₂)
things to wonder about next
- fuel use and crash risk climb steeply with speed, while time saved flattens — the trade gets worse from both sides.
- traffic lights erase most gains in town: average speed, not top speed, decides arrival time.
- the same 1/x shape shows up in download speeds, oven temperatures and adding more staff to a late project.
sources & further reading
concepts: rates · time–distance–speed · diminishing returns
3 minute read