Newton (unit)

For other uses, see Newton (unit) (disambiguation).

The newton (symbol: N) is the SI derived unit of force, named after Sir Isaac Newton in recognition of his work on classical mechanics.

Definition

The newton is the unit of force in the SI system, required to give a mass of one kilogram an acceleration of one meter per second per second.

Algebraically:

${\rm {1~N=1~{\frac {kg\cdot m}{s^{2}}}}}.$

Examples

• 1 N is the force of Earth's gravity on an object with a mass of about 102 g (1⁄9.8 kg) (such as a small apple).
• On Earth's surface, a mass of 1 kg exerts a force of approximately 9.81 N [down] (or 1 kgf). The approximation of 1 kg corresponding to 10 N is sometimes used as a rule of thumb in everyday life and in engineering.
• The decanewton (daN) = 10 N is increasingy used when specifying load bearing capacity of items such as ropes and anti-vibration mounts, being approximately equivalent to the more familiar non-SI unit of force, the kgf (or even less correctly, the kg).
• The force of Earth's gravity on a human being with a mass of 70 kg is approximately 687 N.
• The scalar product of force and distance (N·m)— a force of 1 N exerted over a distance of 1 m— is one joule, the SI unit of energy.
• Because a newton is a small amount of force, it is common to see forces expressed in kilonewtons or kN, where 1 kN = 1 000 N.
• A metric tonne (1 000 kg) exerts a force of 9.8 kN (or 1 000 kgf) under standard gravity conditions on Earth.

References

• Halliday, Resnick and Walker Fundamentals of Physics, John Wiley & Sons ISBN 0471470619

See also

• Joule, the SI unit of energy, equivalent to 1 newton exerted over a distance of 1 metre.
• Pascal, the SI unit of pressure, equivalent to 1 newton acting on an area of 1 square meter.