Mass and weight are important ideas in physics that can be a bit tricky to understand.

Mass: How Much Stuff Is There?

• What is Mass? Mass tells us how much matter is in an object.

• Key Point: Mass stays the same, no matter where the object is. Whether it's on Earth, the Moon, or in space, the mass doesn't change.

• Measurement: The standard unit for mass is the kilogram (kg).

• Example: If an object has a mass of 10 kg, it has that same mass no matter where it is.

Weight: How Strong is Gravity?

• What is Weight? Weight is the force that gravity pulls on an object.

• What Affects Weight? Weight depends on both the mass of the object and how strong gravity is where the object is located.

• How to Calculate Weight: You can find weight using this formula:

  $W = m \cdot g$

  Here, W is weight, m is mass, and g is how fast gravity pulls on it (which is about $9.81 \, \text{m/s}^2$ on Earth).

• Example: A 10 kg object weighs about $98.1 \, \text{N}$ (Newtons) on Earth because $10 \, \text{kg} \times 9.81 \, \text{m/s}^2 = 98.1 \, \text{N}$. But on the Moon, that same object would weigh only about $16.5 \, \text{N}$, since the Moon's gravity is weaker at about $1.63 \, \text{m/s}^2$.

To Sum It All Up: Mass is all about how much stuff there is in an object, and it stays the same everywhere. Weight, on the other hand, is how strongly gravity pulls on that object, and it can change based on where the object is.