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 derived in the SI system; it is equal to the amount of force required to accelerate a mass of one kilogram at a rate of one meter per second per second. Algebraically:

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

Examples

• 1 N is the force of Earth's gravity on an object with a mass of about 102 g (frac: 9.8 kg) (such as a small apple).
• On Earth's surface, a mass of 1 kg exerts a force of approximately 9.80665 N 1 (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 force of Earth's gravity on a human being with a mass of 70 kg is approximately 687 N.
• The dot product of force and distance is mechanical work. Thus, in SI units, a force of 1 N exerted over a distance of 1 m is 1 N·m of work. The Work-Energy Theorem states that the work done on a body is equal to the change in energy of the body. 1 N·m = 1 J (joule), the SI unit of energy.
• It is common to see forces expressed in kilonewtons or kN, where 1 kN = 1 000 N.

Common use of kilonewtons in construction

Kilonewtons are often used for stating safety holding values of fasteners, anchors and more in the building industry. They are also often used in the specifications for rock climbing equipment. The safe working loads in both tension and shear measurements can be stated in kN (kilonewtons).

1 kN equals 101.97162 kilograms of load, but multiplying the kN value by 100 is a good rule of thumb.

See also

• Force gauge
• International System of Units (SI)
• Joule, SI unit of energy, 1 newton exerted over a distance of 1 metre
• Kilogram-force, force exerted by Earth's gravity at sea level on one kilogram of mass
• Pascal, SI unit of pressure, 1 newton acting on an area of 1 square metre