An object's mass, rather than its weight is used to indicate the amount of matter it contains because weight is defined as the amount of force due to an existing field (In most cases, gravitational field) that is experienced by the body. The weight of the same body can be different in different environments it's observed.
However, the mass of the body is the exact measure of the amount of matter contained in a body. Which is constant, regardless of the environment, or conditions the body is observed.
Hence, for real-world calculations and experimentation, the mass of the body is considered to represent the amount of matter it contains rather than its weight.
Learn more about mass here
brainly.com/question/19694949
#SPJ4