What is the SI unit for weight?

The SI unit for weight is the Newton. Weight is the force exerted by gravity on an object, and this force is measured in newtons in the International System of Units (SI). One newton is defined as the amount of force required to accelerate a one-kilogram mass by one meter per second squared. This relationship between force, mass, and acceleration is established by Newton's second law of motion, which states that force equals mass times acceleration (F=ma). Thus, it is clear that the newton serves as the appropriate unit for measuring weight since weight is a gravitational force.

The other choices represent different concepts related to mass and weight but are not the SI unit for weight. Kilograms represent mass, pounds are a unit of weight used predominantly in the United States and not in the metric system, while a kip is a unit of force equal to 1,000 pounds-force, primarily used in structural engineering contexts.