What is the SI unit for force?

The SI unit for force is the Newton, which is represented by the letter "N." This unit is defined as the amount of force required to accelerate a one-kilogram mass by one meter per second squared. This relationship is grounded in Newton's second law of motion, where force equals mass times acceleration (F = ma).

Understanding force in terms of acceleration highlights its dependence on both mass and the rate of change of velocity. Thus, when you apply a force represented in Newtons, you are effectively describing how much "push" or "pull" is being exerted on an object, taking into account its mass and the acceleration experienced.

The other choices represent different concepts; for example, m/s² denotes acceleration, ft lbs/s² is an expression that mixes imperial and SI units and is not considered a standard SI unit, and kg is a unit of mass, not force. Hence, knowing that Newtons measure force allows for proper understanding and application in various physics and engineering contexts.