Describe a point. what could you use as a model of a point ?

A point is an exact location.
It has no length, width, or height.
It has no area or volume.
It has no mass, shape, or other physical properties.

As a model ...

-- you could use the period at the end of a sentence printed on paper.
     It looks like this  ==> ·

-- You could use the point of a very sharp pencil.

-- You could use the tiny dot that the point of
a very sharp pencil makes on paper.

-- You could use the point of a pin.

-- You could use the tiny hole that the point of
a pin makes in a sheet of paper.

These are all bigger than a real point.  They all have a little bit of size,
length, width, height, and you can see them.  But they get the idea across.
(They 'make the point'.)

Bc equals mb that should be your answer