What is the key difference between mass and weight?

The key difference between mass and weight is that mass is a measure of the amount of matter in an object, while weight is the force exerted by gravity on that mass.

Mass is a fundamental property of an object, a measure of the amount of matter it contains. It is measured in kilograms (kg) and remains constant regardless of where the object is in the universe. For example, if you were to travel to the moon, your mass would remain the same as it is on Earth. This is because mass is not affected by changes in gravity or location.

On the other hand, weight is the force exerted on an object due to gravity. It is calculated by multiplying an object's mass by the acceleration due to gravity. Weight is a force, and thus is measured in newtons (N). Unlike mass, weight can change depending on where in the universe the object is. For instance, an object weighs less on the moon than it does on Earth because the moon's gravitational pull is weaker.

In summary, while mass is a measure of the amount of matter in an object and remains constant, weight is the force of gravity on that mass and can change depending on the location. It's important to understand this distinction, especially when studying physics, as it can greatly impact calculations and understanding of different physical phenomena.