Why does the mass of a human differ on the North pole from the mass on the South pole?
if a person travels to canada with a mass of 34kg then why does the mass change when the person travels to australia?
The term “mass” is defined as the quantity of matter in an object. It is a constant for that object, regardless of location in the universe. The mass of an object determines the degree of its resistance to acceleration or deceleration, or change in direction if moving. These are aspects of inertia.
Weight, although related to mass, is not the same thing. The force of gravity on a body is defined as its weight. At any given location in the universe, two objects with the same mass will have equal weights. But if you take two objects of equal mass, and locate them at points with differing distances from the source of gravity (such as the North and South poles of the earth), the object that is closer to the center of the earth will have the higher weight.
A related term is density. It refers to mass per unit volume. Balsa wood has low density compared to high-density lead.
The first reference defines mass and weight, and has simple questions that illustrate your understanding of the two terms.
The second reference further explains the terms, including density.