Newton - Definition and Overview

This article is about the SI unit of force. For other uses see Newton (disambiguation)

In physics, the newton (symbol: N) is the SI unit of force, named after Sir Isaac Newton in recognition of his work on classical mechanics. It was first used around 1904, but not until 1948 was it officially adopted by the General Conference on Weights and Measures (CGPM) as the name for the mks unit of force.

It is defined as the amount of force required to accelerate a mass of one kilogram at a rate of one metre per second squared.

The newton is an SI derived unit, comprising kg × m &times s^-2 in SI base units.

Since one definition of weight is the force acting between two objects due to gravity, the newton is also the unit of weight. A mass of one kilogram near the Earth's surface has a weight of approximately 9.81 newtons, although this figure varies by a few tenths of one per cent over the Earth's surface. Conversely, an object with a mass of 9.81^-1 kg (≈101.94 grams) weighs roughly one newton. Rather fittingly, given the story about Newton's discovery of gravity, this is about the mass of a small apple.

See also

• Sir Isaac Newton
• SI
• dyne, the unit of force of the (mostly obsolete) CGS system, equal to 10 µN.
• kilogram-force