What unit is force measured in?

Force is measured in Newtons, which is the standard unit of force in the International System of Units (SI). The Newton is defined as the amount of force required to accelerate a one-kilogram mass by one meter per second squared (1 N = 1 kg·m/s²). This relationship emphasizes the connection between force, mass, and acceleration, which is famously described by Newton's second law of motion.

The other units listed have distinct meanings and purposes. Kilograms are a unit of mass, not force, while pounds can measure force in certain contexts, particularly in the Imperial system, but they are not widely used in scientific contexts. Joules measure energy, which is the work done when a force is applied over a distance, but they do not directly measure force itself. Thus, Newton is the appropriate unit for force in physics.