Question

What is mass?

Answer 1

@Michele_Laino

great question!

Answer 2

That property of a body which is a measure of its reluctance to change its velocity.

Answer 3

Mass is a two sided concept.In the words of Einstein it is another side of the coin,where one side is energy.
So you could say that mass of something is also how energetic it is.
This is mass energy equivalence!

Answer 4

Farcher! No pellet

Answer 5

You could write a book about mass. Mine is a simple non-relativistic answer.

Answer 6

mass is condensed energy

Answer 7

I think that we can give two answers:
1) Newton would answered that mass is the measure of the inertia of a moving body;
2) Einstein would answered that mass and energy are two complementary quantities, and nuclear reactions are a good example of such complementary aspect.

please refer to my tutorial on nuclear chemistry:
http://openstudy.com/study#/updates/569003b1e4b09cb8736d02b5

Answer 8

Mass is a measure of how much matter is in an object.