- This article deals with the unit of force. For the unit of mass see Pound (mass).
The pound-force is approximately equal to the gravitational force exerted on a mass of one avoirdupois pound on the surface of Earth. Since the 18th century, the unit has been used in low-precision measurements, for which small changes in Earth's gravity (which varies from place to place by up to half a percent) can safely be neglected.
- Main article: wikipedia:Pound-force
- ↑ Acceleration due to gravity varies over the surface of the Earth, generally increasing from about 9.78 m/s² (32.1 ft/s²) at the equator to about 9.83 m/s² (32.3 ft/s²) at the poles.