The history
From Aristotle's falling stones to satellites that clock your bike ride: 2,300 years of learning what 'how fast' means.
For two thousand years people followed Aristotle: heavy things fall faster, and motion needs a push. Oxford scholars in the 1330s and Galileo in the 1600s learned to treat speed as a number that changes, and to measure how quickly it changes. Newton linked acceleration to force, speedometers and radar put speed on every road, and Einstein showed that one speed, light's, can never be reached.
c. 1335
Mean speed rule
William Heytesbury and the Merton Calculators, England
c. 1350s
Velocity–time graph
Nicole Oresme, France
1604
Law of fall (distance ∝ time²)
Galileo Galilei, Italy
1888
Speedometer patent
Josip Belušić, Croatia
1896
Speeding fine
Walter Arnold, England
1899
Car over 100 km/h
Camille Jenatzy, La Jamais Contente
1949
Radar speeding tickets
Connecticut State Police, USA
400 BCE – 1299
Aristotle's picture of motion rules, with a few thinkers like Philoponus testing it by dropping things.
350 BCE
c. 350 BCE
In his Physics, Aristotle taught that a moving thing needs a mover to keep it going, and that heavier bodies fall faster than light ones. It matched everyday sights like a falling leaf, and it ruled for nearly 2,000 years.
Why it mattered. It set the puzzle every later thinker had to solve: what speed and falling really are.
517
c. 517
The Alexandrian scholar John Philoponus wrote that if you drop two weights, one many times heavier, the difference in their fall times is very small. He argued that moving things carry an 'impetus' given to them.
Why it mattered. It was the first recorded doubt, based on dropping things, that heavier means faster.
1300 – 1599
Oxford's Merton scholars and Nicole Oresme treat speed as a quantity that changes, and draw it as a graph.
1335
c. 1328–1350
A group of Merton College scholars began treating speed as a quantity that can change from instant to instant. Heytesbury's rules of about 1335 include the mean speed rule: speeding up steadily, you cover the same distance as moving the whole time at the speed you had halfway through.
Why it mattered. The mean speed rule is s = ½ (u + v) t, three centuries before Galileo tested it.
1350
c. 1350s
Nicole Oresme drew a changing speed as a line of heights over time, so that the area of the shape stood for the distance covered. With it he proved the Merton rule with a simple triangle and rectangle.
Why it mattered. It is the first velocity–time graph, and the idea that the area under it is the distance.
1580 – 1700
Galileo measures falling and rolling, defines acceleration, and Newton ties it to force.
1586
Stevin and de Groot dropped two lead balls, one ten times heavier than the other, about 30 feet onto a board from the New Church tower in Delft. The two thuds sounded as one.
Why it mattered. A real, recorded experiment against Aristotle, years before the more famous Pisa story.
1604
16 October 1604
In a letter to his friend Paolo Sarpi, Galileo stated that a falling body covers distances that grow as the square of the time: 1, 4, 9, 16. He was timing balls rolling down gentle slopes, which slow the fall enough to measure.
Why it mattered. It is the first statement of s = ½ a t² tested against measurements.
1638
In Two New Sciences Galileo defined uniformly accelerated motion as one that gains equal amounts of speed in equal times. He timed bronze balls rolling down a grooved ramp with a water clock, and showed all bodies would fall together without air.
Why it mattered. It is the definition of acceleration still taught today: a = Δv ÷ Δt.
1644
In his Principles of Philosophy, Descartes wrote that a moving body keeps moving in a straight line unless something stops or turns it, and that going round a circle needs something pulling inwards.
Why it mattered. It made direction part of motion, the seed of the idea of velocity.
1673
In Horologium Oscillatorium Huygens published his theorems on circular motion: the pull needed grows with the square of the speed and shrinks with the radius, what we now write as v² ÷ r.
Why it mattered. It explains the huge accelerations of fan blades and spinning drums.
1676
Timing the eclipses of Jupiter's moon Io, Rømer noticed they came late when Earth was far from Jupiter. Light, he concluded, takes time to cross space. His figures implied a speed of roughly 220,000 km/s.
Why it mattered. The fastest speed there is turned out to be finite, and measurable.
1684
Leibniz published his calculus, a method for finding the rate of change at a single instant. Newton had worked out his own version, 'fluxions', in the 1660s. Instantaneous speed is the limit of distance ÷ time over a vanishing interval.
Why it mattered. It gave a precise meaning to what a speedometer shows.
1687
5 July 1687
Newton's Principia set out his three laws of motion. The second says a force produces an acceleration, a = F ÷ m, and the first that without a force velocity stays the same in speed and direction.
Why it mattered. Speed, velocity and acceleration became the language of all mechanics.
1860 – 1960
Cars, speed limits, speedometers and radar guns make speed something everyone measures.
1896
28 January 1896
Walter Arnold was fined for driving at about 8 mph (13 km/h) where the limit was 2 mph, chased down by a policeman on a bicycle.
Why it mattered. Speed limits made measuring speed a legal matter, not just a scientific one.
1899
29 April 1899
Jenatzy's bullet-shaped electric car La Jamais Contente became the first road vehicle to pass 100 km/h, reaching about 105.9 km/h.
Why it mattered. The first car past a hundred was electric, like today's fastest accelerators.
1902
7 October 1902
Croatian inventor Josip Belušić patented an electric speedometer in 1888. Otto Schultze patented the eddy-current speedometer in 1902: a spinning magnet drags an aluminium cup against a spring, turning the needle. Speedometers became standard on cars from about 1910.
Why it mattered. It put instantaneous speed in front of every driver.
1947
1947–1949
Two engineers at the Automatic Signal Company turned wartime Doppler radar into a speed meter. Connecticut State Police tried it in 1947 and began issuing radar speeding tickets in February 1949.
Why it mattered. The Doppler shift of a reflected wave measures speed directly, with no stopwatch.
By the numbers
The fastest anyone has driven on land, from electric cars in 1898 to a jet car that broke the sound barrier in 1997.
1900 – today
Einstein sets the ultimate speed limit, the Moon settles the falling myth, and satellites measure velocity everywhere.
1905
30 June 1905 (received)
In 'On the Electrodynamics of Moving Bodies' Einstein showed that the speed of light is the same for every observer. Velocities then combine as (u + v) ÷ (1 + uv/c²), so nothing with mass can reach c.
Why it mattered. Simple adding of velocities is only an everyday approximation.
1971
2 August 1971
Standing on the airless Moon, astronaut David Scott dropped a hammer and a falcon feather together, live on television. They hit the ground at the same moment, as Galileo had said.
Why it mattered. Without air, heavy and light things fall together.
1995
1995–2000
The Global Positioning System reached full operation in 1995, and in May 2000 its deliberate degradation for civilian users was switched off. Receivers work out speed from the Doppler shift of satellite signals, which is how phones and sat-navs know yours to a fraction of a km/h.
Why it mattered. Anyone can now measure velocity, with direction, anywhere on Earth.
Did you know?
Since 1983 the metre has been defined by light: the distance light travels in 1/299,792,458 of a second. So the speed of light is exactly 299,792,458 m/s.
1 m/s is exactly 3.6 km/h, because an hour has 3,600 seconds and a kilometre 1,000 metres.
By international rules a car's speedometer may read up to 10% plus 4 km/h too high, but never too low.
The first car to go faster than 100 km/h, in 1899, was electric.
Standing still on the equator, you are moving at about 1,670 km/h as the Earth turns.
The people
384 – 322 BCE · Philosopher · Greece
His rule that heavier things fall faster lasted nearly two thousand years.
c. 1313 – 1372/73 · Logician, Merton College · England
Stated the mean speed rule for uniformly changing motion.
c. 1320 – 1382 · Philosopher and bishop · France
Drew speed against time and read distance from the area.
1564 – 1642 · Physicist and astronomer · Italy
Measured rolling balls, defined uniform acceleration and showed all bodies fall alike without air.
1643 – 1727 · Mathematician and physicist · England
Made acceleration the link between force and motion.
1879 – 1955 · Physicist · Germany and Switzerland
Showed that velocities do not simply add and that nothing with mass reaches light speed.
Where it happened
Sources
Dates marked “c.” are approximate, and historians sometimes disagree about who was first. If you spot a mistake, tell us.
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