non-tremolo repetition rate?

Question

with reference to this answer, tremolo notation,

It's not completely clear to me how one should interpret two bars placed on a half-note, in 4/4 (or 2/4) time. I'd always treated a two-bar marking as splitting the base-beat note into four pieces, so two bars on a half-note would mean playing sixteenths. However, some references such as dolmetsch indicate a double-slash half note to be played as eighth notes.

My particular concern in this case is the cello part to Dvorak's New World Symphony. What's the proper interpretation?

Answer 1

While having each slash represent a division of the note into equal halves would be logical, this doesn't hold true when on a half note (or longer note). Rather, a better general rule is that each slash represents the number of beams equal to how many each note would have if written out.

Thus, 2 slashes on a half note mean that the note should be divided into sixteenth-notes (which have 2 beams).