What is the unit of force in the SI system?

The unit of force in the SI (International System of Units) is the Newton. This unit is defined based on the second law of motion formulated by Isaac Newton, where one Newton is the amount of force needed to accelerate a one-kilogram mass by one meter per second squared. This definition illustrates the relationship between force, mass, and acceleration, making the Newton a fundamental concept in both classical mechanics and physics as a whole.

The other options do not represent the unit of force in the SI system. The pound is a unit of force used in the imperial system, while the joule is a unit of energy, which can also be expressed in terms of force but is not directly the unit of force itself. The pascal is a unit of pressure, defined as one Newton per square meter, relating force to area rather than just force alone. Thus, the Newton stands out specifically as the designated SI unit of force.