Well… first thing to look at is unit of measure.
Gravity is 9.8m/s so thats your 980, cm.
But is this accurate in the space you are implementing it in, or should it have an extra 0 to be correct? 9800 mm?
Usually the units are cm, so 980 should be correct, but practice may prove otherwise.
Second.
apply it directly. Just the result of v2 is enough.
There is no need to scale v2 by delta again, since the result of v2 is already the translated vector by frame speed based on gravity.
Third. With simulate physics the gravity speed implementation is fairly accurate, however it is like being in a vacuum the whole time, so keep that in mind.
object mass affects how items move/how much force is needed to get them to move.
Dropping objects of different size doesn’t apply any effect on physics by default anyway.