if an attack does 0 damage but is unblocked can it be added to ur momentum?

Not unless you use some trick to do it. An attack has to do damage (whether it be from actually hitting, or an effect like Burning Knuckle's react) in order for it to go into your momentum during the end phase.

Citing from the upcoming advanced game rules: <applicable line bolded for emphasis>

9.0 The End Phase
During this phase both players clear any cards played during the current turn from their respective card pools.
9.1 The player whose turn it is will clear all cards from their card pool first.
9.1.1 Their opponent will then clear all of the cards from their card pool.
9.2 When clearing their card pool, a player starts with the card furthest to the right of their
card pool, and works their way back one by one until all cards are removed from their card
pool.
9.3 Any card played as a block will be placed in the discard pile.
9.4 Any face down card in the card pool will be placed in the discard pile.
9.5 Any action card will be placed in the discard pile.
9.6 Any asset will be moved to the staging area.
9.7 Any foundation will be moved to the staging area.
9.8 Any attack is placed in the discard pile
9.8.1 If the attack has generated a vitality loss of one or more to the opponent during the
damage step, it may instead be placed in the momentum.

Overall - **Stamp** for Brad

When the rules take effect (April 17th to conicide with SW01 & SCIV01 being legal for tournament play) burning knuckle will no longer go to your momentum as a result of it's R. As the damage from BR's R is done during the block step, not the damage step.

i was just curious cause my friend brought up the point that im magic even if a creature does 0 damage it deal a damage amount regarless of how low it was so if an the card needed damgae to do something it still counts. but i guess not for ufs (