Question

How are mass and weight related?

Answer 1

More mass means more weight that seems something easy.
`W=g·m` where g is the acceleration due to gravity which on the earth surface is arround `9.81"m/s"^2` and it depends on the distance between the earth's core and where you are weighing things.

So greater mass implies greater weight because it has direct proportionality if g is kept constant.

But g is not a universal number. For example g on the moon's surface is around 6 times lower than the earth's. At the moon the object will have the SAME MASS but DIFFERENT WEIGHT because g is different.

So saying I weigh 60kg is not correct. Weight is measured in Newtons, it would be correct to say I weigh 600N on the earth's surface or i weigh 100N on the moon's surface (taking g as `10"m/s"^2`).

Because of this difference it is better to use mass because it doesn't depend of where are you calculating it (well, Einstein's relativity gives some corrections but, forget about this).