Question

Why should mass not be represented by an arrow?

Answer 1

I believe that an arrow in physics represents a change from one form to another or or an absorbance of another form of matter or mass. I learned this concept in Middle School on my Phy. Science class. and since mass can change in number it shouldn't be represented as an arrow for that reason, because it can't always have a definite number representation. I believe that's the answer I'm not 100% positive, I hope this helps

Answer 2

Arrows represent vector quantities, which have both a magnitude (size) and a direction. For example on Earth, weight acts towards the planet's centre due to the effect of the gravitational field, and has a magnitude in Newtons (e.g. 10N). However, mass is a scalar quantity, meaning that it only has a magnitude - it's just the amount of stuff you have. It would be like an arrow without a direction, which of course is not possible (at least not in this universe...)