How is force expressed in the SI system?

Force is expressed in the SI (International System of Units) as newtons. The newton is defined as the amount of force required to accelerate a one-kilogram mass by one meter per second squared. This fundamental relationship links mass, acceleration, and force, making the newton a crucial unit in physics and engineering.

In contrast, pounds represent a unit of force used in the imperial system, and while kilograms are a unit of mass, they do not directly indicate force without context on acceleration. Newton metres are a unit of torque, not force, as they describe the rotational force applied at a distance. Thus, the correct representation for force in the SI system is newtons, providing a standardized way to express this essential physical quantity.