Sir Isaac Newton
1642 - 1727
A brief history
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Sir Isaac Newton was born prematurely on Christmas Day in 1642 in Woolsthorpe-by-Colsterworth, a small village alongside the Great North Road between Grantham and Stamford. He was sickly and was not expected to survive. His father had died just three months before Newton's birth. Isaac went to the King's School in Grantham, some ten miles to the North, lodging in the town during term time. In 1661, he went up to Trinity College in Cambridge as a poor scholar, having to perform menial tasks for the Fellows to earn his keep. He passed his degree in 1665 without distinction, but returned to Woolsthorpe before taking his MA due to the outbreak of the Great Plague causing the University to close.

At Woolsthorpe Manor during his enforced sojourn, he studied the nature of light and the design of telescopes. He conducted experiments with glass prisms to conclude that sunlight was comprised of component colours, and that each colour refracted differently through glass, which led him to develop the reflecting telescope. He returned to Trinity College as a Fellow in 1667, being appointed in 1669 Lucasian Professor of Mathematics, a position occupied in modern times until recently by Prof Stephen Hawking. A falling apple in the orchard at Woolsthorpe had supposedly led Newton to consider whether the force that caused the apple to fall to the Earth was the same force that governed the motion of the Moon around the Earth and of the planets around the Sun. It is thought, however, that this was an explanation provided by Newton himself to conceal the origin of the discovery in his alchemical research. In 1684, Newton surprised Sir Edmund Halley by revealing that he had proved that the force between the planets and the Sun operated according to an inverse square law. Newton's work on viscosity was, by comparison, a mere bagatelle. However, an ideal liquid is still known as a Newtonian liquid, the viscosity of which is the Newtonian viscosity.

Newton was in later life Master of the Royal Mint, where he introduced milled edges on coins to prevent "cropping", and was President of the Royal Society. He invented and built the first reflecting telescope, developed the calculus (though he called it "fluxions"), and developed the binomial theorem, amongst many other achievements.

Aptifirst supplies many instruments that rely upon Newton's work. For example, we have instruments for measuring viscosity, acceleration and force. Click here to take a look at our product range.

Sir Isaac Newton's statue presides over the green in the centre of Grantham, Lincolnshire, UK.

An animation of Newton's Cradle, illustrating Newton's Second Law of Motion.

Newton carved his name in the windowsill of the Old King's School in Grantham*

Newton's Laws of Motion:

First Law:

An object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.

Second Law:

When a force is applied to an object, it accelerates.

The acceleration takes place in the direction of the applied force, and is proportional to the magnitude of the force. It is also inversely proportional to the mass of the object. Commonly, this law is stated as:

Where F is the force (in Newtons, of course!), m is the mass in kg, and a is the acceleration in metres per second squared. Note that F and a are vectors.

Third Law:

To every action there exists an equal and opposite reaction.

Newton's Definition of Viscosity

Translated from "Principia", published in 1687:

"The resistance which arises from the lack of slipperiness of the parts of the liquid, other things being equal, is proportional to the velocity with which the parts of the liquid are separated from one another."

Newtonian Viscosity, the viscosity of a Newtonian or ideal liquid, is one where the viscosity is constant as the rate of shear increases, ie the shear stress is directly proportional to the shear rate: