Question

What is more fundamental mass or weight?

Answer 1

Mass is the most basic property of matter. It is a measure of matter in a substance. Weight on the other hand is force acting on an object. In physics fundamental means anything that is basic , primary or source .

Complete answer:
When it comes to physics, mass is the fundamental quantity.
Definition of mass: it is defined as the amount of matter in a body. Its SI unit is kilogram (kg).
Definition of weight: it is defined as the measure of effect of force of gravity on a body. Its SI unit is Newton(N).
Let us note down few differences between mass and weight to know which is more fundamental:

MASS	WEIGHT
It is a scalar quantity	It is a vector quantity.
It remains the same no matter what location.	It varies from place to place.
It can never be zero.	It can be zero also, for example: In a place where there is no force of gravity.

The main thing to note is that mass doesn’t vary from place to place. Hence it can be taken as a basic characteristic or fundamental unit .

Additional Information:
The weight can be written as: W=mg where;
W=weight, m=mass and g= gravitational force.
The relationship between mass and weight is that an object which has mass 1kg will have a weight =9.8N.

Note: It should be noted that mass cannot vary from place to place as it is the amount of matter in a body. And that amount can never vary with location; on the other hand weight is product of mass and acceleration, hence it will vary from place to place as g varies from place to place.