Projectiles, explosions etc. impose forces or impulses on other physics objects.
However, using one fixed impulse makes it hard to tweak. Some objects should be affected more than others. Making those heavier or lighter can have unwanted effects.

It might be easier to set up categories of objects (small/medium/large object, light/heavy etc) and create a table of forces. E.g. "small explosion pushes small object with force N".
Same for masses. E.g. "small object" always weighs N kg, no matter the size.

This way it might be easier to tweak behavior.