If a rock is sinking in water with constant speed..
how many forces are working on it?
What are *your* thoughts? What is the context of your question?
my thoughts are that there are only two; gravity and water resistance, but my physics book says its three; gravity, water resistance AND buoyancy. i don't understand how buoyancy works in this situation... anyone?
Do you understand how buoyancy works other situations? It is usually the same:
Separate names with a comma.