Q: Is fluid a substance that continually deforms under an applied shear stress? ¶
A: Yes.
Q: Are fluids substances that have zero shear modulus or? ¶
A: Yes, and in simpler terms, a fluid is a substance which cannot resist any shear force applied to it.
Q: Is fluid not entirely obvious? ¶
A: Yes.
Q: Are fluids a subset of the phases of matter and include liquids? ¶
A: Yes, and gases, plasmas, and to some extent, plastic solids.
Q: Are fluids fluid mechanics? ¶
A: Yes, and which is subdivided into fluid dynamics and fluid statics depending on whether the fluid is in motion.