A tree falls in the woods and no one is around to hear it. Is this tree a biotic or an abiotic factor?

The answer is quite simple if answering on a physical level: Yes and No! Yes, it makes a sound, that being a disturbance in the fluidic medium, air. When the tree falls it causes a disturbance in the air pressure field in the woods and that pressure field emanates away from the fallen tree.

Explanation:

after a the power stroke, adp is released, but the cross-bridge formed is still in place. atp then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.