The history
From Aristotle's pushers to springs, twisted threads and quartz crystals: how people learned to see, weigh and name the pushes and pulls that move the world.
For a very long time, force was an idea you argued about, not a thing you measured. Stevin balanced it with a chain of balls, Hooke caught it in a spring, and Coulomb and Cavendish weighed forces far too small to feel. In 1948 the world gave the unit of force a name, the newton, and today sensors measure it everywhere from bathroom scales to particle colliders.
1586
Forces added and split with a rule
Simon Stevin, Dutch Republic
1678
Law of springs published
Robert Hooke, England
1785
Electric force measured with a torsion balance
Charles-Augustin de Coulomb, France
1797–1798
Gravity between lab objects measured
Henry Cavendish, England
1936–1938
Bonded wire strain gauge
Edward Simmons and Arthur Ruge, USA
1948
Unit of force named the newton
9th CGPM, Paris
350 BCE – 1400
Thinkers in Greece, India and Paris argue about what a push is and why a thrown stone keeps flying.
350 BCE
c. 350 BCE
Aristotle split motion into two kinds. Natural motion, like a stone falling to its home on the ground, needs no push. Violent motion, like a cart being dragged, lasts only while something keeps pushing or pulling it.
Why it mattered. His idea that force makes speed, not change of speed, ruled for about two thousand years.
550
c. 550 CE (dating uncertain)
In the Vaisheshika school of Indian philosophy, Prashastapada described a quality called samskara. One kind, vega, keeps a moving thing moving until other forces wear it down. Another, sthitisthapaka, is the springiness that pulls a bent thing back into shape.
Why it mattered. It shows that thinkers in India were puzzling over inertia and elasticity many centuries before Europe.
1350
c. 1340s–1350s
Buridan said a thrower puts a force called impetus into a stone, and the stone carries it along. Air and weight slowly use it up. He even wondered if it would last for ever with nothing to fight it.
Why it mattered. It moved the push from the air into the moving object, a big step towards inertia.
1586 – 1750
Stevin, Galileo, Hooke, Newton and Varignon treat force as something with a size and a direction that can be added, balanced and calculated.
1586
In his book De Beghinselen der Weeghconst (The Principles of Weighing), Stevin hung a loop of equal balls over a triangle with two slopes. The loop does not slide round by itself, so the few balls on the steep side must balance the many on the gentle side. From this he worked out how forces on ramps balance, and how to split one force into two.
Why it mattered. It was the first clear rule for adding and splitting forces, the idea behind force arrows today.
1638
In Two New Sciences, Galileo showed that balls rolling down ramps speed up by the same amount every second. So the steady pull of weight does not give a steady speed, it gives a steady change of speed. The same book also studied how much force it takes to snap a beam.
Why it mattered. It broke Aristotle's link between force and speed and pointed towards force and acceleration.
1678
1676 (anagram), 1678 (answer)
In 1676 Hooke hid a discovery in a scrambled Latin puzzle, ceiiinosssttuv. Two years later he gave the answer, ut tensio, sic vis: as the stretch, so the force. Pull a spring twice as hard and it stretches twice as far.
Why it mattered. Hooke's law is how every spring scale and force meter turns a force into a length you can read.
1687
5 July 1687
In the Principia, Newton defined an impressed force (vis impressa) as an action on a body that changes its state of rest or steady motion. His second law said the change in motion is proportional to the force, and in the same direction. He also showed that two forces combine like the sides of a parallelogram.
Why it mattered. Force stopped being a vague push and became a precise quantity with a size and a direction.
1687
In the same year as the Principia, Varignon published Projet d'une nouvelle mécanique, a book built on combining forces. He used the parallelogram rule to explain levers, pulleys and ramps with geometry.
Why it mattered. It helped make force diagrams with arrows the everyday tool of engineers.
1770 – 1798
Spring balances weigh the shopping, and twisted threads measure the tiny pulls of electric charges and of gravity itself.
1770
c. 1770
Richard Salter made the first spring balance in Britain. Hang a load on the hook, the spring stretches, and a pointer shows the weight. His family firm, George Salter and Co., went on to make spring balances for shops, homes and even steam engines.
Why it mattered. Hooke's law moved out of the lab and into kitchens and markets.
1785
Coulomb hung a light rod from a thin wire and measured how far electric charges twisted it. The twist told him the force. He found that doubling the distance between two charges makes the force four times weaker.
Why it mattered. His torsion balance showed that forces too small to feel could be measured precisely.
1798
1797–1798
Cavendish used a torsion balance to measure the gravity pulling small lead balls towards big ones. The force was only about 0.00000017 newtons. From it he worked out that the Earth is about 5.5 times as dense as water.
Why it mattered. It measured gravity between everyday objects for the first time and connected weight to the mass of the whole planet.
1873 – 2019
Scientists agree on units of force, name the newton, and invent strain gauges and quartz sensors that turn a push into an electrical signal.
1873
A committee of British scientists set up the centimetre-gram-second system and named its unit of force the dyne, from the Greek word for power. One dyne speeds up one gram by one centimetre per second, every second.
Why it mattered. It was an early unit of force built from Newton's law instead of from the weight of a lump of metal.
1901
Engineers liked to measure force by weight: a kilogram-force was the pull of gravity on one kilogram. But gravity is slightly different from place to place. So the conference fixed a standard value, 9.80665 metres per second squared.
Why it mattered. It made the kilogram-force exact, and it separated mass, in kilograms, from weight, which is a force.
1938
1936–1938
Working separately, Simmons and Ruge found that a fine wire glued to a surface changes its electrical resistance when the surface stretches by a tiny amount. They shared the patent, and the gauge was sold as the SR-4. Glue gauges onto a sturdy block of metal and you get a load cell, which turns force into an electrical signal.
Why it mattered. Load cells built on strain gauges are inside most digital scales, cranes and test machines today.
1948
1948 (SI in 1960)
The conference adopted the name newton, symbol N, for the unit of force in the metre-kilogram-second system. One newton speeds up one kilogram by one metre per second, every second. In 1960 the 11th conference made it part of the new International System of Units, the SI.
Why it mattered. Every force in science and engineering is now measured in the same unit, all over the world.
1950
1950 (quartz force sensor 1961)
Squeeze a quartz crystal and it makes a tiny electric charge. In 1950 Kistler and Sonderegger patented a charge amplifier that could read that charge reliably. Their company, founded in 1959, launched a quartz force sensor in 1961.
Why it mattered. Piezoelectric sensors can measure fast, changing forces, like the punch of an engine or a car crash test.
2019
20 May 2019
Since 1889 the kilogram had been a metal cylinder kept near Paris. From 2019 it is defined by a fixed number of nature, the Planck constant. A Kibble balance, invented by Bryan Kibble in 1975, balances a weight against an electromagnetic force to realise it.
Why it mattered. Because a newton is a kilogram times a metre per second squared, the newton now rests on constants of nature too.
1935 – 1983
Physicists find that every push and pull comes from just four basic forces, and catch the particles that carry one of them.
1935
Protons push each other apart, so what holds an atom's centre together? Yukawa proposed a very strong, very short-range force carried by a new particle, later called the meson. The particle was found in 1947, and he won the Nobel Prize in 1949.
Why it mattered. It showed that a force can be carried by a particle, an idea behind all of modern physics.
1983
January and mid-1983
Sheldon Glashow, Abdus Salam and Steven Weinberg had predicted that the weak force and the electromagnetic force are two faces of one force, carried by particles called W and Z. They shared the 1979 Nobel Prize. In 1983 CERN's collider found the W and then the Z.
Why it mattered. It confirmed the picture of four fundamental forces that explains every push and pull we know.
Did you know?
One newton is roughly the weight of a 102 g mass on Earth, about a small apple.
Stevin put his wreath of balls on the title page with the Dutch motto 'Wonder en is gheen wonder': a wonder is no wonder.
One kilogram-force is exactly 9.80665 newtons, because a 1901 conference fixed a standard value for gravity.
The gravity Cavendish measured between his lead balls was about 0.00000017 newtons, the weight of less than two hundredths of a milligram.
One newton is 100,000 dynes, the old centimetre-gram-second unit of force.
The people
384 – 322 BCE · Philosopher · Greece
Taught that every motion needs a mover, an idea that lasted two thousand years.
c. 6th century CE · Philosopher of the Vaisheshika school · India
Described vega, a tendency to keep moving, and sthitisthapaka, the springiness that restores a shape.
c. 1300 – after 1358 · Philosopher · France
Said a thrown stone carries its own impetus, which air and weight slowly use up.
1548 – 1620 · Mathematician and engineer · Flanders (today's Belgium)
Used a loop of balls on a double ramp to show how forces balance and split.
1635 – 1703 · Natural philosopher and inventor · England
Found that a spring's stretch grows in step with the force on it.
1736 – 1806 · Engineer and physicist · France
Measured electric forces by how much they twisted a thin wire.
1731 – 1810 · Natural philosopher · England
Measured the tiny gravity between lead balls and worked out the density of the Earth.
1907 – 1981 · Physicist · Japan
Explained the strong force holding atomic nuclei together, and became Japan's first Nobel laureate.
1905 – 2000 · Engineer · USA
Co-invented the bonded strain gauge while studying how water tanks shake in earthquakes.
1918 – 2015 · Physicist and inventor · Switzerland
Made quartz force and pressure sensors practical with his charge amplifier.
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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