Here's a breakdown of why:

* Newton's Second Law of Motion: This fundamental law states that force (F) is directly proportional to mass (m) and acceleration (a): F = m * a

* Units: Mass is measured in kilograms (kg) and acceleration in meters per second squared (m/s²). Therefore, the unit of force is kg * m/s², which is defined as a Newton.

Other units:

While the Newton is the standard unit, you might sometimes encounter other units for force:

* Dyne (dyn): A smaller unit, used in the centimeter-gram-second (CGS) system. 1 Newton = 10^5 dynes.

* Pound-force (lbf): A unit commonly used in the United States, defined as the force exerted by gravity on a pound mass. 1 lbf ≈ 4.448 N.

* Kilogram-force (kgf): Sometimes used, it represents the force exerted by gravity on a kilogram mass. 1 kgf ≈ 9.807 N.

It's crucial to be consistent with units when working with force calculations, as mixing units can lead to incorrect results.