The difference between mass and weight is fundamental:

• Mass is the amount of matter an object contains. It is a scalar quantity and remains constant regardless of location. Mass measures an object's inertia, or resistance to changes in motion, and is typically measured in kilograms (kg)

• Weight is the force exerted on that mass by gravity. It is a vector quantity and depends on the gravitational field strength at the object's location. Weight is calculated as the product of mass and the acceleration due to gravity (W = m × g) and is measured in newtons (N)

For example, a person with a mass of 70 kg weighs about 686 newtons on Earth (where gravity is approximately 9.8 m/s²), but would weigh less on the Moon due to weaker gravity, even though their mass remains the same

. In summary:

• Mass = amount of matter (constant everywhere)
• Weight = gravitational force on that matter (varies with gravity)

This distinction explains why mass does not change when you travel to different planets, but weight does