What is the difference between mass and weight?

Mass is the amount of matter in an object, while weight is the force of gravity on that object.

Mass is a measure of how much matter an object contains and is usually measured in kilograms (kg). It is a scalar quantity, meaning it only has magnitude and no direction. Mass remains constant regardless of where the object is in the universe. For example, a 1 kg mass on Earth will still have a mass of 1 kg if taken to the Moon or any other planet.

Weight, on the other hand, is the force exerted on an object due to gravity. It is a vector quantity, which means it has both magnitude and direction. Weight is calculated using the formula \( \text{Weight} = \text{Mass} \times \text{Gravitational Field Strength} \). On Earth, the gravitational field strength is approximately \( 9.8 \, \text{N/kg} \). Therefore, an object with a mass of 1 kg will have a weight of \( 9.8 \, \text{N} \) (newtons) on Earth. However, if you take the same object to the Moon, where the gravitational field strength is about \( 1.6 \, \text{N/kg} \), its weight would be significantly less, around \( 1.6 \, \text{N} \).

It's important to note that while mass is an intrinsic property of an object, weight depends on the local gravitational field strength. This is why astronauts feel weightless in space; they are still within the influence of Earth's gravity, but the gravitational force is much weaker, making their weight negligible.

Understanding the difference between mass and weight is crucial in physics, as it helps in analysing forces and motion accurately. Always remember: mass is what you measure on a balance, and weight is what you measure on a scale.